  General characters.—Pelage with lanceolate aristiforms limited to an area on the dorsal surface between the shoulders and the hips; length of tail less than 90 per cent of length of head and body; skull with conspicuous ridges; extension of supraorbital ridges always evident on parietals; infraorbital foramen usually with separate groove for transmission of nerve; palate usually extended posteriorly as far as third molars; incisors opisthodont; molariform teeth with a small main fold, never extended transversely to opposite wall in occlusal surface of tooth; usually one counterfold anterior to main fold in upper molariform teeth and posterior to main fold in lower molariform teeth; premolars usually smaller than first molars, first molars smaller than second molars but second molars larger than third molars. Proechimys goeldiiThomasGeneral characters.—Size large; tail short; aristiforms narrow and soft, usually concealed in pelage by setiforms; general color of upper parts some tint of orange, gradually becoming lighter on sides with no conspicuous, dark longitudinal band on back; feet dark; ventral surface of body and inner side of legs white but sometimes with some buff locally; skull broad and strongly built but not conspicuously ridged; zygomatic expanse great and rostrum not elongate; incisive foramen narrow; bullae large and inflated; upper molariform teeth with three to four counterfolds, M3 ordinarily with four; lower premolars with four, and molars with three, counterfolds. Proechimys goeldii steereiGoldmanProechimys steerei Goldman, Proc. Biol. Soc. Washington, 24:238, 28 November 1911 (original description); Goldman, 1912, Proc. Biol. Soc. Washington, 25:186; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400; Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:119; Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist., 29(13):204. Type locality.—Hyutanaham, Upper Purus, LÁbrea, Amazonas, Brazil. Type: United States National Museum, no. 105535, adult male; collected in 1901 by Prof. J. B. Steere. Range.—Known only from the type locality and Porto Velho. Diagnosis.—Upper parts Mars Orange on back, grading to Ochraceous-Tawny on sides; zygomatic breadth narrow; nasals short; incisive foramen narrow and short; vomerine sheath complete and thick; upper molars usually with four counterfolds. Pelage.—Aristiforms on middorsal region: Grayish basally, gradually blackening toward tip; total length, 16 to 19 mm; maximum width, 0.5 mm. Setiforms on middorsal region: Grayish on basal third, gradually blackening toward tip but interrupted by a Mars Orange, subapical zone 1.5 mm long; total length, 16 to 19 mm; maximum width, 0.06 mm. Setiforms on outer thighs: Whitish basally, gradually blackening toward tip but interrupted by Orange Rufous or Ochraceous-Tawny, subapical zone; total length, 14 to 16 mm; maximum width, 0.05 mm. Figs. 25, 27.Proechimys goeldii steerei, sex ?, "Hyutanaham," USNM no. 105537. × 1. Figs. 26, 28. Proechimys goeldii goeldii, female, AMNH no. 37488. × 1. Figs. 29, 30. Proechimys goeldii steerei, sex ?, USNM no. 105537, "Hyutanaham." × 1. Figs. 31, 32. Proechimys goeldii goeldii, female, AMNH no. 37488, Fazenda Paraiso. × 1. Skull.—Large and strong; rostrum rather pointed posteriorly; supraorbital ridges not much expanded and extending across anterior half of parietals; infraorbital foramen without groove for transmission of nerve, or groove obsolete; zygomatic arches slender; postorbital process of zygoma involving mostly squamosal; incisive foramen short and narrow (4.5 × 2.5 mm) with margins almost parallel or tapering gradually caudad and extending toward palate as ridges; posterior margin of incisive foramen approximately 2.5 mm anterior to premolars; vomerine sheath complete, with both elements well-developed; mesopterygoid fossa never extending anterior to middle of M3; bullae large, well inflated and with shallow grooves. Teeth.—Upper molariform teeth: P4 with three counterfolds; upper molars with four counterfolds each or, less commonly, three. Lower premolars with four counterfolds; lower molars with three each. Comparisons.—From P. g. goeldii, steerei differs in: Back and sides with more reddish; narrower interorbitally and across zygomata; palatilar length less and nasals shorter; maxillary part of vomerine sheath thicker; usually four instead of three counterfolds in M3. Remarks.—This subspecies is clearly related to P. goeldii. One skull from Porto Velho, Rio Madeira, GuaporÉ, Brazil (CNHM no. 21558) may belong to an unnamed subspecies but is provisionally included here. In the field notes of Professor Joseph Beal Steere, an entry for no. 72 reads: "Big white bellied wood rats x two young found in nest of grass on the ground with the two young—much darker young female." No. 77 in his field notes corresponds to the type specimen. Specimens examined.—Total number, 4, from Brazil, as follows: Amazonas. LÁbrea, Hyutanaham, 3 (USNM); Territ. GuaporÉ, Porto Velho, 1 (CNHM). Proechimys goeldii goeldiiThomasProechimys goeldii Thomas, June 1905, Ann. Mag. Nat. Hist., 15 (ser. 7):587, (orig. descr.); Thomas, 1912, Ann. Mag. Nat. Hist., 9 (ser. 8):89; Thomas, 1920, Ann. Mag. Nat. Hist., 6 (ser. 9):277, Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400; Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist., 29(13):199. Proechimys cayennensis goeldii, Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121. Type locality.—Santarem, Santarem, ParÁ, Brazil. Type: British Museum (Nat. Hist.), no. 5.1.25.6, adult female; presented by Dr. E. A. Goeldi. Range.—Margins of the Amazon, between JamundÁ and Tapajoz rivers. Diagnosis.—Upper parts Ochraceous-Tawny; wide across zygomata; nasals of moderate length; incisive foramen long and narrow; vomerine sheath complete but maxillary part slender; first and second upper molars with four counterfolds. Pelage.—Aristiforms on middorsal region: Whitish basally and gradually blackening toward tip which is extended as long, thin filament; total length, 22 to 24 mm; maximum width, 0.5 mm. Setiforms on middorsal region: Gray basally, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone 3.3 mm long; total length, 19 to 21 mm; maximum width, 0.06 mm. Setiforms on outer thighs: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone 3 mm long; total length 14 to 16 mm; maximum width, 0.04 mm. Skull.—Large and strong; nasals pointed posteriorly; supraorbital ridges moderately developed and extended caudad across anterior third of parietals; zygomatic arches strong; postorbital process of zygoma involving mostly squamosal; incisive foramen elongate and narrow (5 to 6.5 × 2.3 mm) with margins more or less parallel and raised to form ridges which extend posteriorly to within 3 mm of plane of premolars; vomerine sheath complete, with maxillary part thin and extended caudad as medial crest; mesopterygoid fossa extending forward as far as posterior faces of second molars or slightly short thereof; bullae large and inflated. Teeth.—Molariform teeth large, P4-M3 averaging more than 9 mm in length. Upper molariform teeth: P4 and M3 with three counterfolds; M1 and M2 with four counterfolds each. In lower teeth, p4 with four counterfolds and each molar with three counterfolds. Comparisons.—Differences from P. g. steerei are given in the account of that subspecies. Remarks.—Specimens from the type locality were not available. Specimens from Fazenda Paraiso, Faro, were relied upon as representative of the subspecies. These agree with the type according to Thomas (1912:89). However, the skin of the type was changed in color by preservative (Thomas, 1905:587) and the best skin he saw was from Faro (1912:89). Thomas (1920:277) applied the name goeldii also to specimens from ManacaparÚ, a place a short distance above Manaus on the SolimÕes (Amazon) River and from Acajutuba, near Manaus, on the Negro River. In referring to these specimens (2 from ManacaparÚ and 2 from Acajutuba) Thomas (loc. cit.) said "Five molar laminae are frequently, if not invariably, present among these specimens." He did not, however, mention whether or not the number of laminae was constant in both M2 and M3. One specimen from Acajutuba, in the collection of Museu Nacional (MN no. 1973 [M]), actually has five laminae in M3, but the specimens in the American Museum from Faro agree absolutely with Thomas' original description of goeldii. Osgood (1944:199) doubted that goeldii was a valid species. Evidence that Osgood's doubt was unjustified is furnished by the fact that Thomas (1912:89) pointed out that his specimen from Faro agrees with the type. Likewise, my two specimens from Faro agree with the type insofar as it has been described. Thomas (1912:89) mentioned two additional skulls from the type locality which, he stated, agree with the type which was received from the Museu Goeldi, ParÁ. Specimens examined.—Total number, 4, from Brazil as follows: ParÁ, Faro, Faro, Fazenda Paraiso, 2 (AMNH); Amazonas, Manaus, Manaus, 1 skull (AMNH); Amazonas, Manaus, Acajutuba, 1 (MN). Additional records.—Total number, 7 (British Museum), from Brazil, as follows: ParÁ, Santarem, Santarem (Thomas, 1912:89; 1920:277), 3; Amazonas, Manaus, Acajutuba (Thomas, 1920:277), 2; ManacaparÚ, ManacaparÚ (Thomas, 1920:277), 2. Proechimys semispinosus(Tomes)Figs. 33, 36.Proechimys semispinosus liminalis, female, MN no. 6253, Rio Quichito. Type. × 1. Figs. 34, 37.Proechimys semispinosus amphichoricus, male, AMNH no. 77020, Mount Duida. Type. × 1. Figs. 35, 38.Proechimys semispinosus kermiti, female, AMNH no. 37124, Lower Rio SolimÕes. Type. × 1.2 (from photograph). General characters.—Size large; tail short and hairy; aristiforms wide and stiff, especially well-developed on back; general color on upper parts some shade of ochraceous, usually much darker on back and forming a conspicuous dorsal band; feet dark; ventral surfaces and inner sides of legs white; skull elongate and strong with ridges well developed; incisive foramen long and narrow; bullae large; usually four counterfolds in M3 and M2; usually three but sometimes four counterfolds in M1 and even P4; lower premolar with four and lower molars with three counterfolds. Figs. 39, 40.Proechimys semispinosus liminalis, female, MN no. 6253, Rio Quichito. Type. × 1. Figs. 41, 42.Proechimys semispinosus amphichoricus, male, AMNH no. 77020, Mount Duida. Type. × 1. Figs. 43, 44.Proechimys semispinosus kermiti, female, AMNH no. 37124, Lower Rio SolimÕes. Type. × 1.2 (from photograph). Proechimys semispinosus liminalis subspecies novaType locality.—Rio Quichito, affluent from the south of the JavarÍ River, near Benjamin Constant, Benjamin Constant, Amazonas, Brazil. Type: Museu Nacional, no. 6253, adult female, collected in August, 1942, by E. Parko. Range.—Known only from the type locality. Diagnosis.—Color uniformly dark, setiforms marked with Ochraceous-Tawny; skull wide across zygomata; nasals short; prepalatilar part of skull long; incisive foramen long and narrow; vomerine sheath incomplete or complete; M2 and M3 almost always with four counterfolds; M1 more rarely with four counterfolds. Pelage.—Aristiforms on middorsal region: Gray basally, gradually blackening toward tip which is generally extended as a filament; total length, 21 to 23 mm; maximum width, 0.9 to 1 mm. Setiforms on middorsal region: Gray basally, gradually blackening toward tip but interrupted by Ochraceous-subapical Skull.—Large and strongly built throughout; supraorbital ridges expanded and thick, extending, in old specimens, across parietals to anterior angles of interparietals; interparietal ridges always conspicuous; rostrum elongated; nasals blunt posteriorly; zygomatic arches strong; infraorbital foramen with weakly-developed groove for transmission of nerve; postorbital process of zygoma involving mostly squamosal; incisive foramen averaging 6 x 2.7 mm, widest in middle part and posteriorly constricted, with raised margins which do not extend across maxillae as ridges; posterior margin of incisive foramen approximately 1.5 mm anterior to plane of premolars; vomerine sheath incomplete or, sometimes, complete but always with maxillary part slender; mesopterygoid fossa not extending forward past centers of third molars; bullae moderately developed. Teeth.—Upper molariform teeth: P4 always with three counterfolds; M1 with three counterfolds in 9 of 10 specimens and four counterfolds in remainder; M2 with four counterfolds in 7 specimens, three counterfolds in remainder; M3 with four counterfolds in 6 specimens, three counterfolds in remainder. Lower premolar always with four, and molars with three, counterfolds. Comparisons.—From P. s. semispinosus, liminalis differs in: darker color; wider aristiforms; greater percentage of upper molars with four counterfolds. From P. s. amphichoricus, liminalis differs in: lighter upper parts of almost uniform color instead of with conspicuous, blackish, middorsal, longitudinal band; more strongly built skull; longer incisive foramen; vomerine sheath usually incomplete instead of always complete. Specimens examined.—Total number, 10 (MN) from the type locality. Proechimys semispinosus amphichoricus subspecies novaType locality.—Mount Duida, Esmeralda, Amazonas, Venezuela; altitude 325 m. Type: American Museum of Natural History, no. 77020, adult male; collected 16 October 1920 by Olalla Bros. Range.—Headwaters of Negro and Orinoco rivers, along boundary of Brazil and Venezuela. Diagnosis.—Color dark, blackish on middorsal area; subapical zone of setiforms on back Buckthorn Brown, but many with distal parts black; skull broad across zygomata; nasals long; prepalatilar area of skull long; incisive foramen long and narrow; vomerine sheath complete; upper molars usually with four counterfolds but P4 usually with only three. Pelage.—Aristiforms on middorsal region: Grayish basally, gradually blackening toward tip; total length, 18 to 20 mm; maximum width, 0.8 to 1.0 mm. Setiforms on middorsal region: Gray basally, gradually blackening toward tip but interrupted by a light (16 i), Buckthorn Brown, subapical zone 2 mm long; total length, 18 to 22 mm; maximum width, 0.03 mm. Most of them, Skull.—Large and slender; rostrum elongate; nasals bluntly pointed posteriorly; supraorbital ridges thick (but not expanded) and extending across parietals but almost obsolete in middle part of parietals; infraorbital foramen with weakly-developed groove for transmission of nerve; postorbital process of zygoma involving mostly squamosal; incisive foramen 5.5 x 2.8 mm wide in anterior third, with margins constricted posteriorly and extending as ridges approximately 2 mm beyond posterior margin of incisive foramen; posterior margin of incisive foramen approximately 2.5 mm anterior to premolars; vomerine sheath complete with maxillary part weak and premaxillary part extending posteriorly beyond middle of incisive foramen; mesopterygoid fossa extending forward as far as middle of M3; bullae well inflated and elongated. Teeth.—P4 with four counterfolds in one of five specimens and with three in remainder; M1 with four counterfolds in three of five specimens and with three in remainder; M2 with three counterfolds in one specimen and with four in all four remaining specimens; M3 always with four counterfolds. Lower premolars with four counterfolds and lower molars with only three. Comparisons.—The subspecies is easily distinguishable from P. s. angularis by: larger number of black setiforms on back, forming an almost black longitudinal band; more elongate skull; larger and longer bulla; longer incisive foramen which is more constricted posteriorly. Specimens examined.—Total number, 6 (AMNH), as follows: Venezuela, territ. Amazonas, Esmeralda, Mt. Duida, altitude 325 m., 4; Venezuela, territ. Amazonas, Rio Cassiquiare, QuemapurÉ, 1; Brazil, Amazonas, SÃo Gabriel, Rio UaupÉs or Caiari, TatÚ, 1. Proechimys semispinosus kermitiAllenProechimys kermiti Allen, 30 December 1915, Bull. Amer. Mus. Nat. Hist., 34(22):629 (orig. descr.); Allen, 1916, Bull. Amer. Mus. Nat. Hist., 35(30):569; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400; Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:119. Type locality.—Lower Rio SolimÕes (up the SolimÕes 50 to 60 miles on the north bank of the river), ManacaparÚ, Amazonas, Brazil. Type: American Museum of Natural History, no. 37124, adult female; collected 20 April, 1914, by Leo E. Miller (Roosevelt Brazilian Expedition). Range.—Known only from type locality. Diagnosis.—Upper parts Tawny, with darker longitudinal band on back, gradually becoming Ochraceous-Buff on sides; zygomata widely spread; nasals long; incisive foramen long; vomerine sheath incomplete; only M3 with four counterfolds. Pelage.—Aristiforms on middorsal region: Grayish basally, gradually blackening toward tip; total length, 18 to 20 mm; maximum width, 0.8 mm. Setiforms on middorsal region: Grayish basally, gradually blackening toward tip but interrupted by Tawny, subapical zone 2 mm long; total length, 18 to 20 Skull.—Large, elongate, and strongly built; rostrum not conspicuously elongated; nasals bluntly pointed posteriorly; supraorbital ridges wide and extending posteriorly across parietals almost to level of interparietal; infraorbital foramen with moderate development of groove for transmission of nerve; zygomatic arches slender; postorbital process of zygoma involving mostly squamosal; incisive foramen 6.5 mm long and 2.7 mm wide, wider in anterior third and gradually constricted posteriorly, with margins extended toward palate as ridges; vomerine sheath incomplete, maxillary part threadlike; mesopterygoid fossa extending forward as far as anterior third of m3; bullae large and well inflated. Teeth.—P4 with three counterfolds; M3 with four counterfolds; M1 and M2 with three counterfolds. Lower premolars with four counterfolds; lower molars with three counterfolds. Comparisons.—From P. s. amphichoricus, kermiti differs in: upper parts Tawny instead of Buckthorn Brown; incisive foramen longer and wider; vomerine sheath incomplete; only M3 instead of usually all molars, with four counterfolds. From P. s. liminalis, kermiti differs in: upper parts Tawny instead of Ochraceous-Tawny; aristiforms narrower; M3 only, instead of usually M2 and M3, with four counterfolds. Specimens examined.—Only the type. Proechimys longicaudatus(Rengger)General characters.—Size medium to large; tail short; aristiforms long and narrow; general color on upper parts Ochraceous-Buff to Ochraceous-Orange, finely and uniformly lined with blackish and not forming evident dark band on back; feet dorsally white or gray; underparts of body and inner sides of legs white; skull elongate and slender with moderate ridges; incisive foramen of medium size; vomerine sheath complete or incomplete; bullae large and elongate; upper molariform teeth with three counterfolds; lower molariform teeth with three counterfolds but commonly one or two molars have only two although premolar may have four. Remarks.—The identity of "Echimys longicaudatus Rengger" can be ascertained only after samples have been collected in the area indicated by Rengger: "unter dem ein und zwansigsten Breitengrade" in Paraguay. Of the samples available to me, those from Urucum, in western Brazil, are geographically nearest the type locality. North of Urucum, both in Brazil and Bolivia, two species of Proechimys live together and one of them is the same species as that at Urucum. Of the two species found to the northward in Brazil and Bolivia, the one that ranges farther south probably will occur at the locality indicated by Rengger. Provisionally, therefore, the name longicaudatus is allocated to the Urucum sample (see Osgood, 1944:198). In fact, the lack of a type specimen and the The form from Urucum, to which the name Proechimys longicaudatus is here applied, is undoubtedly closely related to Proechimys leucomystax Ribeiro, from UtiaritÍ, on the Rio Papagaio and also to P. roberti and P. boimensis, all from Brazil. P. longicaudatus is used as the name of the species because it is the oldest of the four names. Figs. 45, 48.Proechimys longicaudatus boimensis, male, MCZ no. 30881, Boim. × 1. Figs. 41, 42.Proechimys longicaudatus longicaudatus, male, AMNH no. 37085, Urucum. × 1. Figs. 43, 44.Proechimys longicaudatus leucomystax, male, AMNH no. 37509, Tapirapoa. × 1. Figs. 51, 52.Proechimys longicaudatus roberti, male, MN no. 6233, Pouso Alto, Goiaz. × 1. Figs. 53, 54.Proechimys longicaudatus boimensis, male, MCZ no. 30881, Boim. × 1. Figs. 55, 56.Proechimys longicaudatus longicaudatus, male, AMNH no. 37085, Urucum. × 1. Figs. 57, 58.Proechimys longicaudatus leucomystax, male, AMNH no. 37509, Tapirapoa. × 1. Figs. 59, 60.Proechimys longicaudatus roberti, male, MN no. 6233, Pouso Alto, Goiaz. × 1. Proechimys longicaudatus brevicauda (GÜnther)Echimys brevicauda GÜnther, 1 April 1877, Proc. Zool. Soc. London for 1876, (49):748, fig. 9. Proechimys brevicauda Ihering, 1904, Rev. Mus. Paulista, S. Paulo, 6:422; Osgood, 1914, Zool. Ser. Field Mus. Nat. Hist., 10(12):168; Thomas, 1924, Ann. Mag. Nat. Hist., 13 (ser. 9):534; Thomas, 1927, Ann. Mag. Nat. Hist., 19 (ser. 9):553; Thomas, 1927, Ann. Mag. Nat. Hist., 20 (ser. 9):604; Thomas, 1928, Ann. Mag. Nat. Hist., 2 (ser. 10):262; Thomas, 1928, Ann. Mag. Nat. Hist., 2 (ser. 10):292; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68 (5):399; Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist., 29 (13):201. Proechimys cayennensis brevicauda Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:120. Type locality.—Chamicuros, Rio Huallaga, Peru. Type: British Museum (Nat. Hist.), no. 69.3.31.7,[F]; Lectoparatype: British Museum (Nat. Hist.), no. 66.1.29.8, from Upper Amazons (E. Barttet), selected by Thomas (1900:301). Range.—Region of the headwaters and upper courses of the JuruÁ and Ucaiali rivers, eastern Peru and northwestern Brazil. Diagnosis.—Upper parts Tawny and blackish without marked longitudinal band on back; underparts buffy or white; aristiforms narrow; skull slender; incisive foramen wide; vomerine sheath complete; molariform teeth with three counterfolds, except p4 with four and m3 with only two. Pelage.—Aristiforms on middorsal region: Blackish basally, gradually blackening toward tip which is extended as a long filament; total length, 18 to 20 mm; maximum width, 0.65 mm. Setiforms on middorsal region: Gray basally, gradually blackening toward tip but interrupted by Tawny, subapical zone 1.2 mm long; total length, 19 to 21 mm; maximum width, 0.1 mm. Setiforms on outer thighs: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone 3 mm long. Skull.—Slender but not elongated; nasals tapering posteriorly; interparietals wide; supraorbital ridges not much extended and faintly shown across parietals; jugals dorso-ventrally "wide" (3.5 mm); postorbital process of zygoma weakly developed; incisive foramen 5.5 x 3 mm, oval, with posterior borders raised to form ridges which extend toward premolars; vomerine sheath complete, with maxillary part laterally compressed and extended toward palate as ridge; mesopterygoid fossa extending forward as far as third molars; bullae large and well inflated. Teeth.—Molariform teeth with three counterfolds, except p4 which has four and m3 which has only two counterfolds. Comparisons.—From P. l. longicaudatus, brevicauda differs in: upper parts Tawny instead of Ochraceous-Buff; lower premolar with four instead of three counterfolds; m3 only, instead of both m1 and m3, with two counterfolds. From P. l. boimensis, brevicauda differs in: upper parts Tawny instead of Ochraceous-Orange; aristiforms wider; m3 with two instead of three counterfolds. Specimens examined.—Total number, 3 (DZ), from Brazil, Amazonas, JoÃo Pessoa, Rio JuruÁ. Proechimys longicaudatus boimensisJ. A. AllenProechimys boimensis Allen, 24 July, 1916, Bull. Amer. Mus. Nat. Hist., 35(27):523; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400; Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:119. Proechimys cayennensis Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist., 29(13):199. Type locality.—Boim, Rio Tapajoz, Santarem, ParÁ, Brazil. Type: American Museum of Natural History, no. 37486, adult male; "October 10, 1911 (ex Museu Goeldi)." Range.—Along lower course of Tapajoz River. Diagnosis.—Upper parts Ochraceous-Orange; incisive foramen posteriorly constricted; mesopterygoid fossa sharply pointed anteriorly; p4 with four counterfolds, remaining molariform teeth with three counterfolds. Pelage.—Aristiforms on middorsal region: Gray basally, gradually blackening toward tip which is extended as a long filament; total length, 16 to 18 mm; maximum width, 0.5 mm. Setiforms on middorsal region: Gray basally, gradually blackening toward tip, but interrupted by short (1.5 mm), Ochraceous-Orange, subapical zone; total length 18 to 20 mm; maximum width 0.09 mm. Setiforms on outer thighs: White basally, gradually blackening toward tip but interrupted by Ochraceous-Orange, or Ochraceous-Buff, subapical zone 3.5 mm long; total length 15 to 17 mm; maximum width, 0.06 mm. Skull.—Elongate and slender; rostrum slender and long; nasals evenly pointed posteriorly; supraorbital ridges weak and barely reaching anteriormost part of parietals; zygomatic arches slender; infraorbital foramen with groove for nerve-transmission obsolete; postorbital process of zygoma weak and involving mostly squamosal; incisive foramen 5 mm long and 2.5 to 3 mm wide, oval, with margins not much extended caudad as ridges; posterior margin of incisive foramen approximately 2 mm anterior to premolars; vomerine sheath complete with maxillary part slender; mesopterygoid fossa sharply pointed anteriorly and extending forward as far as anterior part of third molar; bullae of medium size, smooth and more or less triangular in contour. Teeth.—Crown length of upper molariform teeth 7 to 7.5 mm; all upper molariform teeth with three counterfolds; lower premolar with four counterfolds; lower molars with three counterfolds each. Comparisons.—From three of the other four subspecies found in Brazil, boimensis differs in having four, instead of three, counterfolds in the lower premolars. Differences from P. l. brevicauda are indicated in the account of that subspecies. Remarks.—The material available from Boim, Tapajoz, is rather poor and of no great significance. The Museu Nacional has one specimen from Boim which agrees with the type in the American Museum of Natural History. The Museum of Comparative ZoÖlogy at Harvard College, however, has one specimen in its collection (MCZ no. 30888 [M]), adult, also from Boim, in which the color pattern is different although agreement with the type specimen is shown in cranial characters and width and length of hairs. This Specimens examined.—Total number, 5, from Brazil, ParÁ, as follows: Santarem, Rio Tapajoz, Boim, 3 (AMNH type, MCZ 1, MN 1); Porto de Moz, TauarÍ, 1 (MCZ); CametÁ (?) 1 (MCZ). Proechimys longicaudatus longicaudatus(Rengger)Echimys longicaudatus Rengger, 1830, Naturgeschichte der Saeugethiere von Paraguay, p. 236. Loncheres myosuros Lichtenstein, 1832, Darstellung neuer oder wenig bekannter SÄugethiere, pl. 36 and text. Echimys myosuros Is. Geoffroy Saint-Hilaire, 1840, Mag. Zool., Ann. 2 (ser. 2):15, 17; Allen, 1899, Bull. Amer. Mus. Nat. Hist., 12(20):261. Echimys cayennensis Pictet, 1841, MÉm. Soc. Phys. Hist. Nat., GenÈve, 9:145; Waterhouse, 1848, Nat. Hist. Mammalia, 2:334. Proechimys longicaudatus Thomas, 1901, Ann. Mag. Nat. Hist., 8 (ser. 7):532; Thomas, 1904, Proc. Zool. Soc. London, p. 240; Allen, 1916, Bull. Amer. Mus. Nat. Hist., 35(30):569; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400. Proechimys cayennensis longicaudatus Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121; Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist, 29(13):198. Type locality.—Northern Paraguay ("unter dem ein und zwansigsten Breitengrade"). Type: Apparently no type specimen was preserved. Range.—Western Mato Grosso, Brazil, and northern Paraguay. Diagnosis.—Upper parts almost uniformly Ochraceous-Buff; incisive foramen widest posteriorly; vomerine sheath complete; p4 and m2 with three counterfolds; m1 and m3 usually with two counterfolds. Pelage.—Aristiforms on middorsal region: Dark gray, gradually blackening toward tip that has long filament; total length 20 to 22 mm; maximum width 0.6 mm. Setiforms on middorsal region: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Buff, subapical zone; blackish tip extended (3.5 mm) and thin; total length 19 to 20 mm; maximum width 0.06 mm. Setiforms on outer thighs: Whitish basally, progressively grayish or blackish toward tip but interrupted by Light Ochraceous-Buff or Ochraceous-Buff, subapical zone; total length 18 to 20 mm; maximum width 0.06 mm. Skull.—Slender; supraorbital ridge notably raised; bullae large, elongate, smooth and inflated; jugals narrow; postorbital process of zygoma of medium size and constructed entirely of jugal; incisive foramen wide and large (5.5 x Teeth.—Upper molariform teeth always with three counterfolds. Lower molariform teeth: p4 and m2 always with three counterfolds, sometimes the two anterior ones coalesced in m2; m1 with three counterfolds in one specimen (33 per cent); m3 with only two counterfolds in all specimens. Comparisons.—Differences from P. l. leucomystax and P. l. roberti are given in the accounts of those subspecies. Specimens examined.—Total number, 3 (2 AMNH, 1 CNHM), from Brazil, Mato Grosso, CorumbÁ, Urucum. Proechimys longicaudatus leucomystaxRibeiroProechimys leucomystax Ribeiro, May, 1914, CommissÃo de linhas telegraphicas estrategicas de Matto Grosso ao Amazonas, Annexo no. 5. Hit. Nat., Zool., Mammiferos, p. 42, pl. 24 (orig. descr.); Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400; Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:119. Type locality.—UtiaritÍ, Rio Papagaio, Diamantion, Mato Grosso, Brazil. Type: Museu Nacional, no. 2212, adult, skull only, collected on 5 May 1909, by Prof. A. Miaranda Ribeiro, is here designated lectotype. See remarks. Range.—Serra dos ParecÍs, Mato Grosso, Brazil. Diagnosis.—Ochraceous-Buff, richly lined with blackish, on upper parts; some setiforms completely blackened distally; incisive foramen regularly ovoid; vomerine sheath incomplete; upper molariform teeth and lower premolar with three counterfolds; m2 with three counterfolds but m1 and m3 usually with two counterfolds. Pelage.—Aristiforms on middorsal region: Grayish basally, gradually blackening toward tip which is extended as a long filament; total length 21 to 22 mm; maximum width 0.65 mm. Setiforms on middorsal region: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Buff, subapical zone; some setiforms grayish basally and gradually blackening toward distal portion without any colored, subapical zone; total length 20 to 22 mm, maximum width 0.06 mm. Setiforms on outer thigh: White basally, gradually becoming gray toward tip but interrupted by Light Ochraceous-Buff, subapical zone; some setiforms gray basally and blackening toward tip, but interrupted by Ochraceous-Buff, subapical zone; total length 15 to 18 mm; maximum width 0.08 mm. Skull.—Slender; supraorbital ridges conspicuous; bullae large, smooth and inflated, with slight, transverse groove; jugals narrow; postorbital processes of zygomata small and involving only squamosal; incisive foramen of medium size but narrow (5 x 2.5 mm), regularly oval and with margins uplifted posteriorly; vomerine sheath incomplete but maxillary part projecting forward and sometimes almost reaching premaxillary part; mesopterygoid fossa reaching forward as far as centers of third molars; posterior palatine foramina at plane of posterior faces of second molars or slightly anterior thereto. Teeth.—Upper molariform teeth with three counterfolds. Lower molariform teeth: p4 and m2 always with 3 counterfolds; m1 and m3 with 2 counterfolds. Comparisons.—From P. l. longicaudatus, leucomystax differs in: upper parts richly lined, instead of scarcely lined, with blackish; incisive foramen narrower, and regularly oval instead of widest anteriorly. Remarks.—Proechimys leucomystax was described mainly on the basis of the UtiaritÍ specimen, here designated lectotype of the species. The specimen from the Juina River is younger, as stated by Ribeiro in his description. Ribeiro mentions the skin of the specimen from UtiaritÍ as "em muito mao estado" and I presume it was discarded as it has not been found in the collection of the Museu Nacional, Brazil. Specimens examined.—Total number, 6, from Brazil, Mato Grosso: CÁceres, Salto Sepotube, 2 (MN); CÁceres, TapirapoÃ, Rio Sepotuba, 2 (AMNH); Diamantino, UtiaritÍ, Rio Papagaio, 1 skull (MN); Diamantino, Rio Juina, 1 (MN). Proechimys longicaudatus robertiThomasProechimys roberti Thomas, December, 1901, Ann. Mag. Nat. Hist., 8 (ser. 7):531 (orig. descr.); Thomas, 1904, Ann. Mag. Nat. Hist., 14 (ser. 7):195; Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):140; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400. Proechimys cayennensis roberti Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121. Type locality.—Rio JordÃo, AraguarÍ, Minas Gerais, Brazil; 960 meters alt. Type: British Museum (Nat. Hist.), no. 1.11.3.62, old male, collected 8 August, 1902, by A. Robert; original number, 705. Range.—Western Minas Gerais and southern Goiaz. Diagnosis.—Color almost uniformly Ochraceous-Orange on upper parts; setiforms long and narrow; incisive foramen long and wide; vomerine sheath usually complete; upper molariform teeth and lower premolar with three counterfolds; m3 with two, and m1 and m2 with two or three, counterfolds. Pelage.—Aristiforms on middorsal region: Whitish basally, gradually blackening toward tip; total length, 21 to 23 mm; maximum width, 0.6 mm. Setiforms on middorsal region: Whitish on basal half, gradually blackening toward tip but interrupted by an Ochraceous-Orange, subapical zone 6 to 7 mm long; total length 25 to 30 mm; maximum width, 0.05 mm. Setiforms on outer thighs: Whitish on basal half, gradually becoming gray and then blackish toward tip but interrupted by wide, Ochraceous-Buff, subapical zone, the tip being brownish or blackish; total length, 22 to 23 mm; maximum width, 0.04 mm. Skull.—Slender; supraorbital ridges bent outward and making sharp angle at point of frontosquamosal suture, then continuing backward parallel to each other and extending across parietals; squamosal taking small part in supraorbital ridges; bullae large (11 x 8 mm), inflated, with shallow depressions; incisive foramen not especially long but wide (5 x 3 to 3.5 mm), widest in anterior third and constricted posteriorly; vomerine sheath usually complete, with maxillary part reduced to slender threadlike process or, less commonly, missing; mesopterygoid fossa extending forward as far as centers of third molars; zygomatic arches strong with jugals of medium dorsoventral width (approximately 3.5 mm); postorbital process of zygoma weakly developed and involving only squamosal; posterior palatine foramina on plane of posterior margins of first molars or slightly anterior thereto. Teeth.—Upper molariform teeth usually with three counterfolds (92.5 per cent of 42 specimens); M2 with four counterfolds in 5 per cent of specimens; M3 with two counterfolds in 2.5 per cent of specimens. Lower molariform teeth: p4 usually with three counterfolds (97.5 per cent of 39 specimens); rarely with four (2.5 per cent); m1 with three counterfolds in 58 per cent and two counterfolds in 42 per cent of specimens; m2 with three counterfolds in 61 per cent and two counterfolds in 39 per cent of specimens; m3 always with only two counterfolds. Comparisons.—From P. l. boimensis, roberti differs in: wider incisive foramen; lower premolar with three, and one or two lower molars with only two, counterfolds, instead of lower premolar with four and all lower molars with three counterfolds. From P. longicaudatus, roberti differs in: upper parts Ochraceous-Orange instead of Ochraceous-Buff; incisive foramen wider in posterior third than in anterior third. Remarks.—This subspecies seems to be adapted to forests of post-climactic conditions which is probably typical of most valleys and margins of the rivers in southern Goiaz and western Minas Gerais. It was found in Goiaz usually in riparian forests with climactic associations or in some advanced stage of the sere. The animals also make incursions into nearby open areas or crops of corn. Specimens examined.—Total number, 52, from Brazil, as follows: Minas Gerais, AraguarÍ, Rio JordÃo (effluent of Parnaiba), 960 meters alt., 2 (1 CNHM, 1 DZ); Goiaz, Anapolis, 1010 meters alt., 38 (MN); Goiaz, Pouso Alto, 768 meters alt., 11 (MN); Goiaz, Tio SÃo Miguel, 2 (MN). Proechimys guyannensis(E. Geoffroy)Mus guyannensis E. Geoffroy Saint-Hilaire, 1803, Catalogue des mammifÈres du Museum d'Histoire Naturelle, Paris, p. 194. Echimys cayennensis Desmarest, 1817, Nouv. Dict. Hist. Nat., Paris, nouv. ed., 10:59. Proechimys cayennensis Allen, 1899, Bull. Amer. Mus. Nat. Hist., 12(20):261, 264; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):399; Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:120. General characters.—Size medium to large; tail usually short; aristiforms narrow to wide; general color of setiforms on back ranging from Tawny to Ochraceous-Buff and becoming gradually lighter on sides; no conspicuous dark longitudinal band on back; upper parts of hands and feet white to light brown; underparts white, including inner sides of legs; skull elongate and not conspicuously ridged; vomerine sheath complete or incomplete; upper premolar with three counterfolds and molars with two or three; lower premolar with three or four counterfolds, and lower molars with two or three. Proechimys guyannensis villicaudasubspecies novaType locality.—TapirapoÃ, Rio Sepotuba, CÁceres, Mato Grosso, Brazil. Type: Museu Nacional, no. 1932, adult male (color faded); collected on 2 February, 1909, by Prof. A. Miranda Ribeiro; original number, 788 A. Range.—Serra dos ParecÍs, headwaters of Paraguai and Tapajoz rivers. Diagnosis.—Aristiforms wide and stiff; general color on upper parts Ochraceous-Orange; incisive foramen long; vomerine sheath incomplete or complete; lower premolar with four counterfolds, remaining molariform teeth with three counterfolds. Pelage.—Aristiforms on middorsal region: Whitish basally, gradually becoming gray toward tip, with distal fourth blackish and ending as a long filament; total length, 22 to 23 mm; maximum width, 1 mm. Setiforms on middorsal region: Whitish on basal half, gradually blackening toward tip but interrupted by Ochraceous-Orange, subapical zone 5 mm long; total length, 26 to 30 Skull.—Strong; supraorbital ridges raised and extending across anterior fourth of parietals; nasals elongate; bullae rounded, inflated, with shallow grooves; postorbital process of zygoma weakly developed and constructed entirely of jugal; incisive foramen elongate and narrow (5.5 x 2.5 mm), posteriorly constricted with posterior margins elevated above surface of bones; vomerine sheath incomplete or complete but, when complete, with maxillary part filiform and delicate; mesopterygoid fossa extending forward as far as middle, or even anterior, parts of third molars; posterior palatine foramina on plane of centers, or even anterior faces, of second molars. Teeth.—Upper molariform teeth with three counterfolds. Lower molariform teeth: premolar with four counterfolds, molars with three counterfolds, sometimes with two folds coalesced in center of tooth. Comparison.—From P. g. ribeiroi, and P. g. bolivianus, villicauda differs in wider aristiforms. From P. g. ribeiroi, villicauda further differs in: larger and wider incisive foramen; vomerine sheath incomplete or complete instead of always complete and thick. From P. g. bolivianus, villicauda differs in: lower premolars always, instead of rarely, with four counterfolds, and m3 always with three counterfolds instead of usually with only two counterfolds. Specimens examined.—Total number, 4, from Brazil, Mato Grosso, as follows: CÁceres, TapirapoÃ, 3 (MN); Diamantino, Rio Papagaio, UtiaritÍ, 1 (AMNH). Fig. 62.Proechimys guyannensis villicauda, male, MN no. 1932, TapirapoÃ. Type. × 1. × 1. Fig. 63.Proechimys guyannensis ribeiroi, male, MN no. 1935, Rio Doze de Outubro. Type. × 1. Fig. 64.Proechimys guyannensis hyleae, male, MCZ no. 30887, TauarÍ. Type. × 1. Fig. 65.Proechimys guyannensis nesiotes, male, CNHM no. 19496, Ilha de ManapirÍ. Type. × 1. Fig. 66.Proechimys guyannensis leioprimna, female, CNHM no. 19503, CametÁ. Type. × 1. Fig. 67.Proechimys guyannensis oris, male, CNHM no. 19495, Providencia. × 1. Fig. 68.Proechimys guyannensis arescens, male, CNHM no. 26440, Fazenda Inhuma. Paratype. × 1. Fig. 69.Proechimys guyannensis riparum, female, AMNH no. 143018, Manaus. Type. × 1. Fig. 70.Proechimys guyannensis arabupu, male, AMNH no. 75816, Arabupu. Type. × 1. Fig. 71.Proechimys guyannensis villicauda, male, MN no. 1932, TapirapoÃ. Type. × 1. Fig. 72.Proechimys guyannensis ribeiroi, male, MN no. 1935, Rio Doze de Outubro. Type. × 1. Fig. 73.Proechimys guyannensis hyleae, male, MCZ no. 30887, TauarÍ. Type. × 1. Fig. 74.Proechimys guyannensis nesiotes, male, CNHM no. 19496, Ilha de ManapirÍ. Type. × 1. Fig. 75.Proechimys guyannensis leioprimna, female, CNHM no. 19503, CametÁ. Type. × 1. Fig. 76.Proechimys guyannensis oris, male, CNHM no. 19495, Providencia. × 1. Fig. 77.Proechimys guyannensis arescens, male, CNHM no. 26440, Fazenda Inhuma. Paratype. × 1. Fig. 78.Proechimys guyannensis riparum, female, AMNH no. 143018, Manaus. Type. × 1. Fig. 79.Proechimys guyannensis arabupu, male, AMNH no. 75816, Arabupu. Type. × 1. Figs. 80, 81.Proechimys guyannensis villicauda, male, MN no. 1932, TapirapoÃ. Type. × 1. Figs. 82, 83.Proechimys guyannensis ribeiroi, male, MN no. 1935, Rio Doze de Outubro. Type. × 1. Figs. 84, 85.Proechimys guyannensis hyleae, male, MCZ no. 30887, TauarÍ. Type. × 1. Figs. 86, 87.Proechimys guyannensis nesiotes, male, CNHM no. 19496, Ilha de ManapirÍ. Type. × 1. Figs. 88, 89.Proechimys guyannensis leioprimna, female, CNHM no. 19503. Type. × 1. Figs. 90, 91.Proechimys guyannensis oris, male, CNHM no. 19495, Providencia. × 1. Figs. 92, 93.Proechimys guyannensis arescens, male, CNHM no. 26440, Fazenda Inhuma. Paratype. × 1. Figs. 94, 95.Proechimys guyannensis riparum, female, AMNH no. 143018, Manaus. Type. × 1. Figs. 96, 97.Proechimys guyannensis arabupu, male, AMNH no. 75816, Arabupu. Type. × 1. Proechimys guyannensis ribeiroisubspecies novaType locality.—Rio 12 de Outubro, affluent of the CamararÉ, Mato Grosso, Mato Grosso, Brazil; about 190 kilometers west of UtiaritÍ; altitude 414 meters. Type: Museu Nacional, no. 1935, adult male (colors faded); collected on 20 June, 1909, by Prof. A. Miranda Ribeiro; original number G. Range.—Known only from the type locality. Diagnosis.—Aristiforms wide and stiff; incisive foramen small and narrow; vomerine sheath complete and thick; p4 with four counterfolds; remaining molariform teeth with three counterfolds. Pelage.—Aristiforms on middorsal region: Whitish basally, gradually blackening toward tip; total length, 19 to 22 mm; maximum width, 0.8 mm. Setiforms on middorsal region: Whitish on basal half, gradually blackening toward tip but interrupted by subapical zone probably of some tint of ochraceous; total length, 22 to 24 mm; maximum width, 0.06 mm. Setiforms on outer thighs: Whitish basally, gradually blackening toward tip but interrupted by probably light ochraceous, subapical zone; total length 14 to 16 mm; maximum width, 0.03 mm. Skull.—Slender; supraorbital ridges low; bullae ovate with shallow grooves; postorbital process of zygoma almost obsolete and involving mostly jugal; incisive foramen short and narrow (4 × 2 mm), constricted posteriorly and with posterior margins raised; vomerine sheath complete and thick; mesopterygoid fossa extending forward as far as posterior faces of second molars; posterior palatine foramina on plane with centers of second molars. Teeth.—Upper molariform teeth with three counterfolds. Lower molariform teeth: p4 with four counterfolds; molars with three counterfolds which sometimes are fused. Comparisons.—From P. g. bolivianus, ribeiroi differs in: aristiforms wider; incisive foramen shorter and narrower; vomerine sheath complete and thick, instead of complete or incomplete and not thick; p4 always with four, instead of usually only three, counterfolds and lower molars always with three, instead of sometimes with only two, counterfolds in m3. Differences from P. g. villicauda are given in the account of that subspecies. Remarks.—The name ribeiroi is given in honor of the late Professor Alipio Miranda Ribeiro, in recognition of his important work in Brazilian vertebrate zoology. Specimens examined.—Total number, 2 (MN), from Brazil, Mato Grosso, Mato Grosso, Rio 12 de Outubro; altitude, 414 meters. Proechimys guyannensis hyleaesubspecies novaType locality.—TauarÍ, Rio Tapajoz, Porto de Moz, ParÁ, Brazil; approximately 87 kilometers south of Santarem. Type: Museum of Comparative Zoology at Harvard College, no. 30887, adult male; collected on 19 January, 1934, by A. M. Olalla; original number 7288. Range.—Region of lower Tapajoz River and banks of Amazon up to the JamundÁ River. Diagnosis.—Aristiforms conspicuously wide and stiff; general color on upper parts Tawny; incisive foramen long and oval; vomerine sheath complete Pelage.—Aristiforms on middorsal region: Whitish basally, gradually becoming blackish toward tip; total length, 19 to 21 mm; maximum width, 1.1 mm. Setiforms on middorsal region: a. Gray basally, gradually blackening toward tip but interrupted by wide (5 to 6 mm) Tawny, subapical zone; some are whitish basally and gradually become sooty brown toward tip except for same type of subapical zone (tip only slightly darker than subapical zone); b. With the same type described above and some completely blackish, with the base gray; total length 22 to 25 mm; maximum width, 0.1 mm. Setiforms on outer thighs: Whitish basally, gradually becoming gray and then blackish toward tip but interrupted by long, Ochraceous-Tawny, subapical zone; tip, itself, blackish brown; sometimes this type appears with some lighter ones and sometimes with completely blackish setiforms; total length 16 to 18 mm; maximum width 0.3 mm. Skull.—Medium in size and slender; cranium narrow and not increasing much in breadth posteriorly; rostrum stout, laterally thick, with masseteric crest well-developed; nasals pointed posteriorly; supraorbital ridges broad but barely extended across parietals; zygomatic arches strong; postorbital process of zygoma involving mostly squamosal; incisive foramen long and narrow (5.5 to 6 × 2.5 mm), oval and extending posteriorly to point only 2 mm anterior to premolars; vomerine sheath complete with maxillary part usually slender; mesopterygoid fossa extending forward as far as centers of third molars; bulla of medium size, well inflated and with shallow grooves on surface. Teeth.—Upper molariform teeth with three counterfolds. Lower premolar with four counterfolds or, sometimes (20 per cent of 15 specimens), with only three; lower molars with three counterfolds. Comparisons.—From P. g. oris and P. g. nesiotes, hyleae differs in: wider aristiforms; general color on upper parts Tawny, instead of Ochraceous-Orange; vomerine sheath not always complete, instead of always complete. From P. g. oris, hyleae differs in: p4 usually with four, instead of only three counterfolds and all molars with three, instead of only lower molars with three counterfolds. From P. g. nesiotes, hyleae differs in: p4 usually, instead of always, with four counterfolds; color on back Tawny instead of Ochraceous-Orange; aristiforms wider. Remarks.—This subspecies shows greater variability than any other in this species. There are two types of coloration. The most common type of coloration is dark, with Tawny, subapical zones in the setiforms of the middorsal region and many completely black setiforms; in the other type the subapical zone is still Tawny but there are no black setiforms. One specimen from Obidos, on the north bank of the Amazon, completely agrees in the characteristics of color and skull with the reddish type and suggests either that there is an extension of the range of the subspecies along the lower Between 13 and 23 January, 1934, A. M. Olalla collected 10 adult females, 6 of which contained embryos. Three of the females had 2 embryos each, two had 3 embryos each and one had only 1 embryo. At this same time and place only ten per cent of specimens obtained were not fully adult. Specimens examined.—Total number, 21, from Brazil, ParÁ, as follows: Porto de Moz, TauarÍ, right bank of Tapajoz, approximately 85 kilometers south of Santarem, 20 (19 MCZ, 1 CNHM); Obidos, Obidos, 1 (MCZ). Proechimys guyannensis nesiotessubspecies novaType locality.—Ilha de ManapirÍ, Rio Tocantins, ParÁ, Brazil. Type: Chicago Natural History Museum, no. 19496, adult male; collected on 9 December, 1910, by Dr. Emilia Snethlage; original number, 12. Range.—Known only from the type locality. Diagnosis.—Aristiforms wide and stiff; general color on upper parts Ochraceous-Orange; incisive foramen long, with parallel borders; vomerine sheath complete and thick; p4 with four counterfolds, remaining molariform teeth with three counterfolds. Pelage.—Aristiforms on middorsal region: Gray basally, gradually blackening toward tip; total length, 18 to 19 mm; maximum width, 0.9 mm. Setiforms on middorsal region: Gray basally, gradually blackening toward tip but interrupted by Ochraceous-Orange, subapical zone 4 mm long; total length 16 to 19 mm; maximum width, 0.06 mm. Setiforms on outer thighs: Whitish basally, gradually becoming gray and blackish toward tip but interrupted by Ochraceous-Buff, subapical zone 3 mm long; total length, 13 to 15 mm; maximum width, 0.03 mm. Skull.—Of medium size; rostrum short; nasals pointed posteriorly; postorbital ridges extending caudad across anterior fifth of parietals; zygomatic arches strong; jugal with process in posterior part of masseteric fossa; postorbital process of zygoma involving mostly squamosal; incisive foramen elongate, narrow (5 x 2.3 mm), and parallel sided; posterior margin of incisive foramen approximately 3 mm anterior to premolars; margins of foramen raised to form ridges; vomerine sheath complete, of almost uniform width and set deeply in foramen; mesopterygoid fossa extending forward as far as centers of third molars; bullae of medium size and inflated. Teeth.—Upper molariform teeth with three counterfolds; p4 with four counterfolds; m1-3 with three counterfolds. Comparison.—From P. g. oris, nesiotes differs in: Aristiforms conspicuously wider; incisive foramen shorter and narrower, with borders parallel instead of posteriorly constricted; posterior margin of incisive foramen farther from premolars; p4 with four, instead of three, counterfolds; lower molars with three instead of two counterfolds. From P. g. leioprimna, nesiotes differs in: Incisive foramen with parallel borders instead of oval; p4 with four instead of three counterfolds; m3 always with three instead of two counterfolds. Remarks.—Dr. E. Snethlage mentions the type as having been collected at night in the forest. Specimens examined.—Total number, 8 (MCZ, CNHM, MN), from Brazil, ParÁ, Tocantins River, Ilha de ManapirÍ. Proechimys guyannensis leioprimnasubspecies novaType locality.—CametÁ, left bank of Tocantins River, near its mouth, CametÁ, ParÁ, Brazil. Type: Chicago Natural History Museum, no. 19503, adult female; collected on 21 January, 1911, by Dr. Emilia Snethlage; original number, 35. Range.—Known only from type locality but probably extending westward toward XingÚ River. Diagnosis.—Aristiforms wide and stiff; general color on upper parts Ochraceous-Orange, incisive foramen moderately long; oval; vomerine sheath complete; all molariform teeth with three counterfolds, except lower, third molar which has only two. Pelage.—Aristiforms on middorsal region: Gray basally, gradually blackening toward tip which is extended as a short filament; total length, 19 to 21 mm; maximum width, 0.8 to 1 mm. Setiforms on middorsal region: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Orange, subapical zone 2 to 3 mm long; total length, 17 to 20 mm; maximum width 0.1 mm. Setiforms on outer thighs: Whitish basally, becoming gradually gray and then blackish toward tip but interrupted by Ochraceous-Buff, subapical zone; blackish tip short; total length 13 to 15 mm; maximum width 0.06 mm. Skull.—Of medium size; rostrum relatively short; nasals with posterior borders rounded; postorbital ridges extending across anterior fourth of parietals; zygomatic arches moderately strong; postorbital process of zygoma involving both jugal and squamosal; incisive foramen of medium length (4 to 5 mm) and narrow (about 2.5 mm), oval and extending caudad to a plane approximately 2 mm anterior to premolars; vomerine sheath complete, with premaxillae forming approximately anterior 3/4 of sheath; maxillary part of sheath short but well-developed; mesopterygoid fossa extending forward as far as centers of third molars; bullae of medium size but well-inflated. Teeth.—Upper molariform teeth with three counterfolds. Lower molariform teeth with three counterfolds, except third molar which has only two. Comparison.—From P. g. oris, leioprimna differs in: conspicuously wider aristiforms; shorter and narrower incisive foramen; lower molariform teeth with three counterfolds (except m3 with only two), instead of lower molars with only two counterfolds. Differences from P. g. nesiotes are given in the account of that subspecies. Remarks.—The paratype was collected in an "igarapÉ," depression usually invaded by the river waters; the paratype, collected on 18 January, 1911, had two large embryos. Specimens examined.—Total number, 4 (2 CNHM, 2 AMNH), from Brazil, ParÁ, CametÁ. Proechimys guyannensis orisThomasProechimys oris Thomas, September, 1904, Ann. Mag. Nat. Hist., 14 (ser. 7): 195; Thomas, 1905, Ann. Mag. Nat. Hist., 15 (ser. 7):587; Thomas, 1912, Ann. Mag. Nat. Hist., 9 (ser. 8):89; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68:400; Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist., 29:199. Proechimys cayennensis oris Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121. Type locality.—IgarapÉ-assÚ, E. F. B., near Belem, IgarapÉ-assÚ, ParÁ, Brazil. Type: British Museum (Nat. Hist.), no. 4.7.4.78, old male; collected on 6 March, 1904, by Alphonse Robert; original number, 1818. Range.—Probably most of the region on south bank of Amazon River, between Tocantins (west) and GurupÍ River (south). Diagnosis.—Aristiforms narrow but somewhat stiff; color on upper parts Ochraceous-Orange; incisive foramen long and wide, conspicuously constricted posteriorly; posterior margin of incisive foramen close to plane of premolars; vomerine sheath complete but maxillary part threadlike; upper molariform teeth and lower premolar with three counterfolds; lower molars with only two counterfolds. Pelage.—Aristiforms on middorsal region: Gray basally, gradually blackening toward tip, which is extended as a filament; total length, 16 to 17 mm; maximum width, 0.6 to 0.7 mm. Setiforms on middorsal region: Gray basally, gradually becoming blackish toward tip but interrupted by Ochraceous-Orange, subapical zone 2 to 4 mm long; total length, 18 to 20 mm; maximum width 0.06 mm. Setiforms on outer thighs: Whitish basally, gradually becoming blackish toward tip but interrupted by Ochraceous-Buff, subapical zone; total length, 15 to 16 mm; maximum width, 0.04 mm. Skull.—Of medium size; supraorbital ridges well developed and extending across anterior fifth of parietals; zygomatic arches strong; jugal with masseteric fossa deep and with well-developed posterior process; postorbital zygomatic process involving mostly squamosal; incisive foramen long (6 to 7 mm), widest anteriorly (2.5 to 3.2 mm); but narrowing posteriorly to less than 1 mm and extending caudad almost to plane of premolars; vomerine sheath complete but maxillary part delicate and threadlike; mesopterygoid fossa extending forward as far as third molars or posterior parts of second molars; bullae large and inflated. Teeth.—Each upper molariform tooth with three counterfolds. In lower jaw, premolar with three, and molars with only two, counterfolds. Comparisons.—Differences from the subspecies with adjoining ranges are given in the accounts of those subspecies. Remarks.—Thomas (1912:89) extended the known range of the subspecies to Faro, on the JamundÁ River, on the left bank of the Amazon, and to Boim, on the Tapajoz River, as well as to Benevides, E. F. Braganca, near Belem. It seems to me that the specimens from Faro should be referred provisionally to Proechimys guyannensis hyleae; the specimens from Boim are "more brightly E. Snethlage collected one specimen in a garden (Providencia, E. F. B.). However, according to the personnel of the Brazilian Health Service, the animals are strictly forest dwellers although they do make excursions into more open places. Specimens examined.—Total number, 3, from Brazil, ParÁ, as follows: Providencia, E. F. B., approximately 15 kilometers east from Belem, 1 (CNHM); TanaquarÁ, near Belem, 1 (MN); Rio GuamÁ, near Belem, 1 (AMNH). Additional record.—Brazil, ParÁ, Benevides, E. F. B., approximately 100 kilometers north-east of Belem (Thomas, 1912:89). Proechimys guyannensis arescensOsgoodProechimys cayennensis arescens Osgood, 12 July 1944, Zool. Ser. Field Mus. Nat. Hist., 29(13): 198. Type locality.—Fazenda Inhuma, below Santa Filomena, upper Rio Parnaiba, Vitoria do Alto Parnaiba, MaranhÃo, Brazil. Type: Chicago Natural History Museum, no. 26441, adult male; collected on 5 August, 1925, by Heinrich E. Snethlage. Range.—Region including the valleys of the TurÍ-assÚ and Parnaiba rivers, MaranhÃo, Brazil. Diagnosis.—Aristiforms moderately wide and not conspicuously stiff; general color of upper parts near (15'a) Ochraceous-Orange; incisive foramen long and wide; vomerine sheath complete or incomplete; upper molariform teeth and lower premolar with three counterfolds; lower molars with only two. Pelage.—Aristiforms on middorsal region: Whitish basally, gradually blackening toward tip; total length, 19 to 21 mm; maximum width, 0.7 mm. Setiforms on middorsal region: Whitish basally or on basal half, gradually becoming gray and then blackish toward tip, but interrupted by long (5 to 6 mm) subapical zone near (15'a) Ochraceous-Orange; total length, 15 to 16 mm; maximum width 0.05 mm. Setiforms on outer thighs: Whitish on basal half, gradually becoming gray and then blackish toward tip but interrupted by Ochraceous-Buff, subapical zone; tip sometimes not conspicuously darker than subapical zone; total length 18 to 25 mm; maximum width, 0.03 mm. Skull.—Medium in size, not elongated; nasals pointed posteriorly; supraorbital ridges strong and thick, extending caudad across anterior third of parietals; zygomatic arches strong; postorbital process of zygoma involving only squamosal; incisive foramen 5 by 2.7 mm, oval and extending caudad to plane approximately 2 mm anterior to premolars; posterior margins of incisive foramen not forming a ridge; vomerine sheath complete and with maxillary part slender and threadlike, or incomplete, in which event, maxillary part not extended enough to join premaxillary process; mesopterygoid fossa Teeth.—Upper molariform teeth with three counterfolds each. Lower premolar with three counterfolds; lower molars with two counterfolds. Comparisons.—From P. g. oris, arescens differs in: Color of upper parts lighter and more uniform; incisive foramen oval instead of conspicuously constricted posteriorly; posterior margin of incisive foramen farther from premolars. Remarks.—One specimen from TurÍ-assÚ (MN) has been identified by O. Thomas as "P. oris" (his own handwriting is on the label) and the subspecies is really closely related to oris. Specimens examined.—Total number, 3, from Brazil, MaranhÃo, as follows: Vitoria do Alto Parnaiba, Fazenda Inhuma (below Santa Filomena), 2 (CNHM); Alto da Alegria, TurÍ-assÚ, 1 (MN). Proechimys guyannensis riparumsubspecies novaType locality.—Manaus, Manaus, Amazonas, Brazil. Type: American Museum of Natural History, no. 143018, adult female; collected 6 March, 1943. Range.—Known only from type locality but probably extending northward and eastward. Diagnosis.—Aristiforms wide and stiff; upper parts Ochraceous-Tawny; incisive foramen short, wide, and oval; vomerine sheath incomplete; upper molariform teeth and lower premolar with three counterfolds; lower molars with only two counterfolds. Pelage.—Aristiforms on middorsal region: Gray basally gradually blackening toward tip; total length, 18 to 20 mm; maximum width, 0.9 mm. Setiforms on middorsal region: Whitish basally, gradually blackening toward tip but interrupted by 2 mm long, Ochraceous-Tawny, subapical zone; total length 20 to 22 mm; maximum width, 0.04 mm. Some are whitish basally and gradually become black toward tip with no subapical zone. Setiforms on outer thighs: Whitish basally, gradually becoming gray and then blackish toward tip but interrupted by Ochraceous-Buff, subapical zone 3 to 4 mm long; tip not conspicuously dark; total length, 17 to 19 mm; maximum width, 0.03 mm. Skull.—Of medium size and slender; rostrum slender; nasals rounded posteriorly; supraorbital ridges well developed and barely extended onto anteriormost part of parietals; zygomatic arches slender; infraorbital foramen with well-developed groove for nerve transmission; postorbital process of zygoma almost obsolete and involving mostly squamosal; incisive foramen short and wide (4.5 × 3.3 mm), oval and with posterior margins raised to form ridges which extend toward premolars; posterior margin of incisive foramen approximately 2.5 mm anterior to premolars; vomerine sheath incomplete, with only short, premaxillary part; mesopterygoid fossa extending forward as far as anterior parts of third molars; bullae large and inflated, with more or less triangular outline. Teeth.—Crown length of well worn P4-M3, 6.8 mm; upper molariform Comparisons.—From P. g. oris and P. g. hyleae, riparum differs in: Shorter and wider incisive foramen; vomerine sheath incomplete, instead of sometimes incomplete. From P. g. oris, riparum differs in: Upper parts Ochraceous-Tawny instead of Ochraceous-Orange; aristiforms conspicuously wider. From P. g. hyleae, riparum differs in: Aristiforms narrower; upper parts Ochraceous-Tawny instead of Tawny; lower premolars with three, instead of four, counterfolds; lower molars with two, instead of three, counterfolds. Specimens examined.—Type only. Proechimys guyannensis arabupu subspecies novaType locality.—Arabupu, Mount Roraima, Boa Vista, Territ. Rio Branco; about 1540 meters altitude. Type: American Museum of Natural History, no. 75816, adult male; collected by Dr. G. H. H. Tate on 30 December, 1927; original number, 4716. Range.—Known only from the type locality. Diagnosis.—Aristiforms conspicuously wide and stiff; color on upper parts dark, near (15'j) Ochraceous-Tawny; incisive foramen widest in anterior third; vomerine sheath complete, sometimes incomplete; upper molariform teeth and lower premolar with three counterfolds; lower molars with two counterfolds. Pelage.—Aristiforms on middorsal region: Whitish basally, gradually blackening toward tip; total length, 19 to 22 mm; maximum width, 1.1 mm. Setiforms on middorsal region: Gray basally, gradually blackening toward tip but interrupted by dark (15'j) Ochraceous-Tawny, subapical zone 3 mm long; some completely blackish on distal parts; total length, 20 to 23 mm; maximum width, 0.07. Setiforms on outer thighs: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Buff or Light Ochraceous-Buff, subapical zone; total length, 20 to 23 mm; maximum width, 0.07 mm. Skull.—Size medium; nasals pointed posteriorly; supraorbital ridges prominent and slightly extended caudad onto anterior half of parietals; groove for transmission of nerve in infraorbital foramen weakly developed; zygomatic arches strong; postorbital process of zygoma involving mostly squamosal; incisive foramen approximately 5.5 × 2.7 mm, widest in anterior third and constricted posteriorly, with posterior margin about 1 mm anterior to plane of premolars; vomerine sheath complete, with premaxillary part expanded and maxillary part notably slender and sometimes lacking; mesopterygoid fossa in some specimens extending forward as far as middle parts of second molars; bullae large and inflated. Teeth.—Upper molariform teeth with three counterfolds each. Lower premolar with three counterfolds; molars with only two. Comparisons.—From P. g. warreni, arabupu differs in: Narrower aristiforms; narrower incisive foramen; lower premolar with three instead of four counterfolds; lower molars with two, instead of three, counterfolds. From P. g. oris, arabupu differs in: Aristiforms wider; posterior margin of incisive foramen farther from plane of premolars; upper parts dark (15'j) Ochraceous-Tawny, instead of Ochraceous-Orange. Remarks.—The sample is fairly uniform. Specimens examined.—Total number, 6 (AMNH), from Brazil, Territorio do Rio Branco, Boa Vista, Mount Roraima, Arabupu; approximately 1540 m. altitude. |
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