CHORDATA. 199 



Order 2. Ungulata. Hoofed mammals, with elongated metaearpals 

 and metatarsals, and two successive sets of enamel-covered teeth. Cla- 

 vicles never present; never more than four digits. 



(a.) Artiodactyla, paired digits, and grinding teeth with enamel folds. 

 Placenta diffuse or cotyledonary, 



Non-ruminantia (Bunodontia). Anthracotherium, a primaeval 



3 1 4 



form from the Eocene. Porcus babymssa. Sus scrofa, pig, 3" y "4 



Sus antiquus, Miocene. Hippopotamus amphibius. 



Ruminantia (Bisulca, Pecora, Selenodontia), with complicated 

 stomach; median upper incisors always absent. Anoplotherium, 

 Miocene. Camelus. Auchenia, llama. Helladotherium and Siya- 

 therium, Miocene. Camelopardalis giraffus. Dorcatherium, Mio- 

 cene. Tragulus, chevrotain, recent Megaceros Hibernicus, Irish elk, 

 Pleistocene. Ceryus capreolus, roe, 0. elaphus, red deer, C. alces, 

 elk. Capra. Ovis. Bos primigenius, B. brachyceros, B. frontosus. 



J>.) Perissodactyla, a large middle digit (3rd) symmetrical in itself, 

 pes with an odd number of toes. Placenta diffuse. Lophiodon, 

 Palseotherium, and Eohippus, in the Eocene. Tapirus, S. America 

 and S.E. Asia. Rhinoceros, S. Africa and S. Asia, 



