388 A MANUAL OF DENTAL ANATOMY. 



time of the animal ; the first premolar, however, is rarely 

 (if ever in recent species) lost, the second being the first to 

 fall out, and then the third. As the fourth is never lost, in 

 most adult bears the first and fourth premolars are found, 

 with a wide interval between them. The premolars of 

 bears thus form an exception to the rule that when a tooth 

 is lost from the premolars, the loss takes place from the 

 front of the series. 



The fourth upper premolar (carnassial tooth) retains 

 something of its carnassial character ; the first lower molar 

 very little, save that it is a narrower and more elongated 

 tooth than the other true molars. 



The true molars are squarish or oblong teeth, raised into 

 blunt tubercular cusps ; they vary in different species. 



In the sloth bear (Ursus labiatus) the incisors are small 

 and the median pair are lost early ; it is variously stated 

 to be frugivorous and to feed on ants, the latter probably 

 being the more truthful account. 



CARNIVORA PINNIPEDIA (SEALS). 

 The aquatic Carnivora are divided into three families : 



I. The Otariida3, or Eared Seals, comprising- the single genus Otaria 



known as Sea Lions, or Sea Bears. These are the " fur Seals,'" 

 from which seal skin is procured, and they are less removed 

 from the terrestrial carnivora than are the other seals : the 

 limbs are better adapted for walking, there are external 

 ears, &c. 



II. The Phocida3, to which family the Seals of our own coasts 



(Phoca greenlandica, &c.) and the Great Proboscis Seals of the 

 southern seas (Cystophora) belong. 



III. The Trichechidas, or Walruses, an aberrant Arctic family con- 

 sisting of one genus only. 



The dentition of the seals is less highly specialised than 

 that of other carnivora, in some cases approximating to that 

 of homodont cetaceans. 



The canines are generally well marked by being larger 



