€HAP. II] THE MAMMALIA 31 



Order 2. Aquatic Eutheria with large head, fish-like body 

 •devoid of hairy covering, the pectoral limb paddle-like, the pelvic 

 limbs absent, and with a horizontal caudal fin. The clavicles 

 {collar bones) are absent, and the pelvis is vestigial. Teeth may 

 be absent and replaced by sheets of baleen (or whalebone). The 

 •conformation of the nostrils and of the larynx is peculiar. 

 Cetacea. 



Order 3. Aquatic Eutheria with moderate-sized head, with 

 porpoise-like body covered with a scattered covering of hairs : the 

 pectoral limbs are paddle-like, the pelvic limbs absent. The 

 •clavicles are absent and the pelvis is vestigial. Teeth are present, 

 and the palate bears rugose horny plates. The larynx is not 

 modified as in the Cetacea. Sirenia. 



Order 4. Terrestrial, chiefly herbivorous Eutheria, with hairy 

 •covering abundant or scanty ; the terminal phalanges of the digits, 

 upon which the weight of the body usually falls, nearly always 

 invested with solid horny hoofs. The clavicle is absent. The 

 teeth are heterodont and diphyodont ; the scaphoid and lunar 

 bones of the carpus (wrist) are always distinct. The digits are 

 •often reduced in number. Ungulata. 



Order 5. Eutheria, chiefly carnivorous, with furry integument : 

 ■digits in manus and pes never less than four, and all provided 

 with claws more or less retractile. The clavicle is variable in its 

 presence, but it is never complete. The teeth are heterodont and 

 diphyodont. The scaphoid and lunar elements of the carpus 

 {wrist) are always united ; the brain usually highly developed. 

 •Carnivora. 



Order 6. Vegetable-feeding Eutheria, mostly small in bulk, 

 with furry or spiny integument, clawed digits and usually planti- 

 grade limbs. The dentition is heterodont and diphyodont, and 

 the form of the incisors is chisel-like : these teeth grow from 

 persistent pulps. Rodentia. 



Order 7. Insectivorous Eutheria with nose usually prolonged 

 into a short soft muzzle ; with furry or spiny integument, clawed 

 digits, and usually pentadactyle plantigrade limbs. Clavicles are 

 present. The dentition is heterodont and diphyodont, and the 



