0. 0. Marsh — Description of Tertiary Artiodactyles. 263 



There appear to have been five digits in the manus, and the 

 same number in the pes, although probably only four were 

 functional. The animal was about the size of a small rabbit. 



The present genus with the one next described represent a 

 distinct family, which may be called the Homacodontidw. 



After the establishment of the genus Ho?nacodon, by the 

 writer, in 1872, Cope proposed the name Pantolestes for a 

 small animal from essentially the same horizon. The type was 

 a lower jaw, with the teeth too imperfect for exact determina- 

 tion, but the animal was referred to the Lemuroids.* This 

 reference was subsequently strengthened by Cope, who placed 

 this specimen in the genus NotharcUis of Leid}^, with 

 Pantolestes as a synonym. f Afterwards he revived the name 

 Pantolestes, and placed under it remains of Artiodactyles, 

 some evidently pertaining to the genus Homacodon, and later 

 still he included other species, but none of them apparently 

 distinct from that genus. 



7. 8. 9. 10. 



Figure 7. — Tibia of Homacodon vagans ; (type) distal end. t, tibia; /, fibula. 

 Figure 8. — Astragalus of same individual ; front view. 

 Figure 9. — Tibia of Nanomeryx caudatus, Marsh ; distal end. 

 Figure 10. — Astragalus of same species ; front view. 



All the figures are twice natural size. 



Nanomeryx caudatus, gen. et sp. nov. 



This genus appears to be nearly related to Homacodon, with 

 which it agrees in several respects, but may be distinguished 

 from it by the fact that the fibula is reduced, and coossified 

 distally with the tibia. The lower jaws are more slender and 

 compressed than in Homacodon, and there is a short diastema 

 between the canine and first lower premolar. The bones of 

 the skeleton, even the vertebrae, are very hollow. 



* Proc. Amer. Philos. Soc, vol. xii, p. 467, for 1872. 

 f Sixth Ann. Rep. IT. S. Geol. Surv. Terr., p. 549, 1873. 



