:\rESODONTA. 
147 
from the Eocene of Wyoming, as to suggest relationsliip. The premolars 
are totally different. 
Apheliscus insidiosus, Cope. 
Aplieliscus insidiosus, Cope, System. Cat. Yert. ISTew Mexico, U. S. Gcog. Survs. W. of 
100th M., 1875, p. 17. 
Prototomus insidiosus, Cope, Eeport on the Yertebrata of New Mexico, U. S. Geog. 
Survs. W. of 100th M., 1874, p. 14; Id. Auu. Eeport TJ. S. Geog. Survs. W. 
of ICOth M., 1874, p. 12G. 
Eepresented in the collections of the Survey by parts of the maxillary 
bone and both mandibular rami with teeth. The species is much smaller 
than the preceding, and differs materially in the forms of the teeth. The 
two anterior tubercles of the tubercular molars are similar and approxi¬ 
mated ; the posterior are slightly divergent, and on the last tooth inclose a 
third of small size. The last premolar has a broad heel and stout antero¬ 
median cone, but no anterior tubercle. The tooth immediately preceding 
is much smaller, and also possesses a heel. The mandibular ramus is par¬ 
ticularly slender, and the angle is not inflected. 
Length of the last two inferior molars... 0. OOGO 
Length of the last molar.....^_ 0. 0034 
width of the last inferior molar.. .. 0. 0020 
Depth of the ramus at last inferior molar... 0. 0045 
Length of the last premolar. . 0. 0030 
Elevation of the same... 0. 0028 
SAECOLEMUE, Cope. 
Sarcolemur, Cope, Proc. Acad. Nat. Sci. Phila., 1875, p. 25G. 
Awtiucodow, “ Marsh,'’Cope, System. Cat. Yert. New Mexico, U. S. Geog. Survs. W. 
of 100th M., 1875, p. 17; Anu. Eept. U. S. Geol. Surv. Terrs., 1872, p. G08. 
Inferior molars 4-3, the last with a heel. Anterior inner cusp of the 
true molars bifid or double; the external cusps subcrescentic in section; 
all the cusps subequally develo|)ed. Last premolar with an inner, and 
sometimes anterior cusp. 
This genus is nearly related to Hyopsodus in the dentition described, 
differing in the double inner anterior cusp of the inferior true molars. The 
type, S.furcatus, Cope (Ann. Kept. U. S. Geol. Surv. Terrs., 1872, p. 609), 
possesses an almost sectorial character of the last premolar. This tooth 
has, besides a median compressed cusp, a stout anterior one. 
