Basilar length (of Hensel).—From the anteriormost border of the foramen magnum to a line connecting the posterior margins of the alveoli of the first upper incisors. F to F' on fig. 31.

Condylobasal length.—Least distance from a line connecting the posteriormost parts of the exoccipital condyles to a line connecting the anteriormost projections of the premaxillary bones.

Length of tooth-rows.—Least distance between a line connecting posterior borders of upper molars and a line connecting anterior faces of middle upper incisors. G to G' on fig. 31.

Breadth of rostrum.—Least distance from lateral base of hamular process of lacrimal bone to corresponding point on opposite side of skull. B to B' on fig. 31.

Interorbital breadth.—Least distance across top of skull between orbits (eye sockets). O to O' on fig. 31.

Orbitonasal length.—Distance on anterior part of skull from posterior margin of base of postorbital process of frontal bone to posteriormost part of anterior border of nasal bone on same side of skull. A to A' on fig. 31.

Mastoid breadth.—Greatest distance across mastoid bones perpendicular to long axis of skull. E to E' on fig. 31.

Zygomatic breadth.—Greatest distance across zygomatic arches of cranium perpendicular to long axis of skull. D to D' on fig. 31.

Tympanic bulla:

Length.—From posterior face to most anterior part of anterior border. H to H' on fig. 31.

Breadth.—From bottom of pit immediately posterior to external auditory meatus to medial face of bulla at right angle with longitudinal axis of skull. J to J' on fig. 31.

Depth.—Least distance from ventral face of basioccipital, excluding median ridge, to line touching ventralmost points of the two bullae. L to L' on fig. 31.

m1, Length.—Greatest length which rarely or never is alveolar length.

P4.—

Lateral.—Length from posterior margin of tooth to anteriormost part of the protocone (anterolateral cusp).

Medial.—Length from the posterior margin of tooth to anteriormost part of the deuterocone (anterointernal cusp).

M1.—

Breadth.—Distance from medial edge of crown to lateral margin of crown, approximately at a right angle with longitudinal axis of the skull.

Length.—Greatest diameter, anteroposteriorly, of the inner lobe or inner half of the tooth.

Depth of skull at anterior margin of basioccipital.—Measured from anterior end of ventral face of basioccipital, excluding median ridge, vertically to dorsal face of parietal excluding sagittal crest. K to K' on fig. 31.

Depth of skull at posterior borders of Ms1.—Measured from ventral face of palatine bones at posterior edge of upper molars to dorsal face of frontals in plane of postorbital processes of frontals. S to S' on fig. 31.