MAMMALS. 13 



X Anterior and posterior limbs and pelvis well developed ; 

 femur and humerus not exserted beyond the common 

 integuments of the body. 



a. Feet with developed claws ; canines specialized ; molars, 

 one or more, sectorial, adapted for cutting; incisors 

 ■f ; chiefly carnivorous. . . Carnivora, A. 



aa. Feet with hoofs; molars mostly with grinding surfaces; 

 incig^ors various; no tusks; developed toes, four or 

 fewer; chiefly herbivorous. . . Ungulata, B. 



ff Brain with a relatively small cerebrum, leaving behind much 

 of the cerebellum exposed, and, in front, much of the 

 olfactory lobes. (Ineducabilia.) 



b. Canine teeth present, in some form ; incisors not f nor f . 



c. Anterior limbs adapted for flight; ulna and radius 

 united; bones of hand and fingers much elon- 

 gated, supporting a thin, leathery skin, extending 

 along sides of bod}- to the posterior limbs; 

 mammae pectoral. . . Ciiitioptera, C 



cc. Limbs all adapted for w^alking ; ulna and radius not 

 united; hand normal; mammae usually abdomi- 

 nal Insectivora, D. 



bb. No canine teeth ; incisors f , rarely f , chisel shaped ; 

 limbs adapted for walking. . Rodentia, E. 



** Young born when of very small size and incomplete develop- 

 ment, never connected by a placenta to the mother; corpus 

 callosum rudimentary. (Didelphia.) . Marsupialia, F. 



A. FAMILIES OF CARNIVOBA. 



* Intestinal canal provided with a ccECum ; feet digitigrade ; toes 

 5-4. 



f Teeth 28 .to 30 ; head broad ; snout short ; claws sharp, 

 retractile . . Felid.e, 1. 



ff Teeth 38 to 4G ; snout elongated ; claws bluntish, non- 

 retractile Canid^, 2. 



** Intestinal canal without a coecum; feet plantigrade, or, if not, 

 toes 5-5. 



