180 STUDIES FOR STUDENTS 



The Carnivora vera are distinguished by the larger size of 

 the brain with its deeper convolutions and the development of a 

 single tooth in each jaw, the fourth premolar in the upper jaw 

 and the opposing first molar in the lower jaw, as sectorial teeth. 

 The suborder is generally divided into two groups : the Fissipeda 

 or land living forms and the Pi?inipeda, seals, walruses, etc. 



Fissipeda. — Seven families are recognized, the Canidae, Ursi- 

 dae, Procyonidae, Mustelidae, Viverridae, Hycenidae and Felidae. 



Canidae. — The dogs appeared in the Upper Eocene of Europe 

 and the Lower Miocene of the United States. They are descend- 

 ants, probably, of the Proviverrine branch of the Creodo?ita. The 

 development of the dogs has been toward the improvement of 

 the feet as organs of locomotion ; the early forms had five toes 

 on both the fore and the hind feet, but in the modern forms the 

 first digit is wanting on the front foot and often on the hind 

 foot as well. The teeth have developed from low crushing forms 

 to the more typical carnivorous condition with the specialized 

 carnassials. Typical forms are : 



Cynodictis and Cephalogale , Upper Eocene, Europe. 



Amphicynodon, Oligocene, Europe. 



Amphicyon and Galecy?ius, Miocene, Europe. 



Daphcenos and Oligobwris, North American Miocene. 



The recent forms appeared in the Pliocene of Europe, Asia 

 and North America, and in the Pleistocene of Africa and South 

 America. 



Ursidae. — The bears are distinguished by the plantigrade feet 

 and the low multitubercular teeth without the specialized carnas- 

 sials. They appeared in the Middle Miocene of Europe in the 

 genus Hycs?iarctos and not before the Pleistocene in the other 

 countries when the existing genera were developed. 



Procyonidae. — The coons occupy a small place somewhere 

 between the dogs and the bears. They were developed some 

 time in the Pliocene and are today confined to the Ameri- 

 can and the South Asian regions. They are known from the 

 Loup Fork beds of the United States. 



Mustelidae. — The weasels and otters are amonsf the most 



