Alf, R.

1962. A new species of the rodent Pipestoneomys from the Oligocene of Nebraska. Breviora, Mus. Comp. Zool., no. 172, pp. 1-7, 3 figs.

Galbreath, E. C.

1953. A contribution to the Tertiary geology and paleontology of northeastern Colorado. Univ. Kansas Paleont. Cont., Vertebrata, art. 4, pp. 1-120, 2 pls., 26 figs.

Hough, J., and Alf, R.

1958. A Chadron mammalian fauna from Nebraska. Journ. Paleon. 30: 132-140, 4 figs.

Jepsen, G. L.

1934. A revision of the American Apatemyidae and the description of a new genus, Sinclairella, from the White River Oligocene of South Dakota. Proc. Amer. Philos. Soc., 74:287-305, 3 pls., 4 figs.

McKenna, M. C.

1960. Fossil Mammalia from the early Wasatchian Four Mile fauna, Eocene of northwest Colorado. Univ. California Publ. in Geol. Sci., 37:1-130, 64 figs.

Matthew, W. D.

1909. The Carnivora and Insectivora of the Bridger Basin, Middle Eocene. Mem. Amer. Mus. Nat. Hist., 9:289-567, pls. 42-52, 118 figs.

Patterson, B. and McGrew, P. O.

1937. A soricid and two erinaceids from the White River Oligocene. Geol. Ser., Field Mus. Nat. Hist., 6:245-272, figs. 60-74.

Scott, W. B. and Jepsen, G. L.

1936. The mammalian fauna of the White River Oligocene—Part I. Insectivora and Carnivora. Trans. Amer. Philos. Soc., n. s., 28:1-153, 22 pls., 7 figs.

Simpson, G. G.

1944. Tempo and mode in evolution. New York: Columbia Univ. Press, xviii + 237 pp., 36 figs.

1953. The major features of evolution. New York: Columbia Univ. Press, xx + 434 pp., 52 figs.

Transmitted June 24, 1963.