SCIUKIDJ3— EXTINCT SPECIES. 939 



slender, with the tubercle at the anterior margin of the masseteric fossa under 

 the centre of the second molar. The crown of the tooth has an anterior 

 transverse crest and a pair of posterior tubercles. From the lower Tertiary 

 deposits, Henry's Fork, Wyoming. 



TILLOMYS PARVUS Marsh. 



TiUomijs parvus Marsh, Amer. Journ. Sci. and Arts, 3d ser. iv, 1872, 219. 



Considerably smaller than the preceding. Length of lower molar series 

 7.1 mm . Described from a similar imperfect lower-jaw fragment containing 

 the second molar, from Grizzly Buttes, Wyoming. 



