CATALOGUE 



OF 



FOSSIL MAMMALIA. 



PART III. 



Order UNGULATA. 



Suborder PERISSODACTYLA. 



The present suborder and the Artiodactyla 1 , which are sometimes 

 grouped together under one name (Ungulata Vera 2 , Diplarthra 3 , or 

 Clinodactyla 4 ), are differentiated from the other suborders of the 

 Ungulata by the structure of the carpus and tarsus. In the carpus 

 the scaphoid is supported by the magnum, and the latter (together 

 with the unciform) supports the lunar ; while in the tarsus the 

 cuboid extends inwardly to articulate with the astragalus, which is 

 deeply grooved. All the bones of both the carpus and tarsus strongly 

 interlock, and the structure of these joints is more complex than in 

 any of the other suborders. No known form has more than four 

 functional digits to either foot ; and the feet are always digitigrade. 

 The jugal forms the anterior part of the. zygomatic arch, and the 



1 Supra, Part II. 



2 Flower, 'Encyclopaedia Britannica,' 9th edit. vol. xv. p. 427 (1883). The 

 term Ungulata Yera is not equivalent to the other terms, since, while Flower 

 (he. cit.) divides the Ungulata into two primary groups only, Cope (inf. cit.) 

 and Marsh (inf. cit.) recognize four such primary groups. In the Cat. Vert. 

 Anim. Mus. Roy. Coll. Surg. part ii. Mammalia (1884), Flower discards all 

 divisions above those of subordinal value ; this arrangement being adopted in 

 the present Catalogue. 



3 Cope, Proc. Amer. Phil. Soc. vol. xx. p. 444 (1882). 



4 Marsh, 'Monograph of the Dinocerata' (Rep. U.S. Geol. Surv. vol. x.), 

 p. 177 (1884). 



PART III. B 



