THE FLESH-EATING PREDATORY MAMMALS 115 



not only closely resembling existing carnivorous Marsupials, but 

 even the dentition of the Theriodont reptiles. There were in 

 each jaw at least three pairs of incisors, one pair of tusk-like 

 canines, four pairs of premolars, and three of molars : the typical 

 mammalian formula of forty-four teeth.^ 



Modern Carnivora are divided into two sub-orders: the 

 Fissipdia, or separate-toed flesh-eaters (dogs, cats, civets, weasels, 

 bears) ; and the Pinnipedia, or web-toed fish-eaters (sea-hons. 



v//mi 



Angle of lower jaw of 

 Wolf. 



Angle of lower jaw of Cams cancrivorus 

 (Crab-eating Dog of Central and South 

 America). 



Angle of lower jaw of Otocyon 

 megalotis. 



ANGLE OF THE LOWER jAW IN Otocy07l, AS COMPARED WITH THE ANGLE OF THE jAW IN 



Cayiis cancrivorus (Crab-eating Dog) and in Wolf. 



1 So far as I am aware no Creodont (unless it is so with Proviverra) 

 has ever been discovered which possessed more than three true molars, 

 and yet there is one remarkable problem in the descent of the Carnivores 

 which has not yet been solved. In South and East Africa is found a 

 curious aberrant dog, called the long-eared fox {Otocyon megalotis). This 

 creature has four pairs of molars in the lower jaw, and very often four 

 in the upper. A fourth molar makes its appearance in the lower jaw 

 of dogs of the genus Canis occasionally, and an increase of molars to four 

 or more appears as a common feature in existing or extinct Marsupials. 

 On the other hand, no existing Marsupial has more than three permanent 

 premolars. One of these teeth, however, is preceded by a " milk " premolar, 

 which may be the missing fourth of this series of teeth. In extinct 

 mammals that are supposed to have been Marsupials, four premolars 

 are present. On the other hand, in these extinct Marsupials with four 

 premolars, there would appear to be only three molars. It would almost 



