4S GUIDK TO THE FOSSIL MAMMALS AND BIRDS. 



Wall-case and represents a group allied Ixjtli to the latter and to the 



^ o Hyracoidea. A skull and mandible (Fig. 38) and an im- 

 Case S. - 111 1 • / , ci 1 



mature skuli are mounted m Lase o, and numerous remains 



are arranged in ^^'all-case 22. The teeth are deei)ened for the 



effective grinding of dry vegetation, while the canine teeth 



are quite small and crowded between the continuous regular 



series of premolars and incisors. There is one pair of small 



bony horn-cores above the eye, and there is an immense pair 



of horn-cores in front, which seem to be the excessively 



enlarged nasal bones. These horn-cores, like the rest of the 



large skull, are formed l)y a mere hollow shell of Ijone, and 



the grooves for Ijlood- vessels in their surface suggest that they 



were oriijinallv covered with a sheath of true horn. 



Sub-order 6. — Hyracoidea. 



^i6^-^^se The small existing hyraxes of Africa, Arabia, and Syria, 



are the scarcely altered survivors of a group of Eocene 

 hoofed mammals allied to the Amblypoda and Condylarthra. 

 They seem to have originated in the African region, and jaws 

 of one hyracoid {Megalohyrax eocamus), as large as a donkey, 

 are shown from the Upper Eocene of the Fayujn, Egypt 

 (Pier-case 21). Pliohyrax, from the Lower Tliocene of 

 Pikermi (Greece), the Isle of Samos, and ^Maragha (Persia), 

 must have been equally large. 



Sub-order 7. — Condylarthra. 

 -^^^^■^^s® These are the small primitive five-toed hoofed animals 



21 



of the Eocene period, which might serve very well for the 

 ancestors of all later Ungulata. They occur both in Europe 

 and Xorth America, Init the most satisfactory specimens 

 have been found in the latter country. Phenacodus (Figs. 

 39,40), of which a plaster cast of a nearly complete skeleton 

 is exhibited in Pier-case 9, is a typical example. Fragments 

 of jaws of Condylarthra are also shown in Pier-case 21. 



Sub-orders 8-10. — Typotheria, Toxodontia^ and 

 Litopterna. 



Pi6^-<l^ses South America seems to have l)een separated from the 



Table-case ^^^^ *^^ ^^^ world during the greater part of the Tertiary 



11.' period, and its indigenous hoofed mammals, commonly 



