FORM. 297 



animals, the genus Tarsipes is remarkable for the paucity as well 

 as minuteness of its teeth. The Elephant has never more than 

 one entire molar, or parts of two, in use on each side of the 

 upper and lower jaws, to which are added two tusks, more or less 

 developed in the intermaxillary bones. Some Rodents, as the 

 Australian Water-rats, {Hydromys), have two grinders on each side 

 of both jaws ; which, added to the four cutting teeth in front, 

 make twelve in all : the common number of teeth in this order 

 is twenty ; but the Hares and Rabbits have twenty-eight teeth. 

 The Sloth has eighteen teeth. The number of teeth, thirty-two, 

 which characterises Man, the Apes of the old world, and the true Ru- 

 minants is the average one of the Class Mammalia. The examples 

 of excessive number of teeth are presented, in the order Bruta, 

 by the Priodont Armadillo, which has ninety-eight teeth ; and, in 

 the Cetaceous Order, by the Cachalot, which has upwards of sixty 

 teeth, though most of them are confined to the lower jaw, — by the 

 common Porpoise, which has between eighty and ninety teeth, — 

 by the Gangetic Dolphin, which has one hundred and twenty teeth, 

 and by the true Dolphins {Delphinus), which have from one hundred 

 to one hundred and ninety teeth, yielding the maximum number 

 in the class Mammalia. 



126. Form. — Where the teeth are in excessive number, as in 

 the species above cited, they are small, equal, or sub-equal, and of 

 a simple conical form : pointed and sHghtly recurved in the common 

 Dolphin ; with a broad and flattened base in the gangetic Dolphin {Inia); 

 with the crown compressed, and broadest in the Porpoise ; compressed, 

 but truncate, and equal with the fang in the Priodon. The simple 

 dentition of the smaller Armadillos, of the Orycterope, and of the 

 three-toed Sloth presents a difference in the size, but little variety 

 in the shape of the teeth, which are sub-cylindrical with broad 

 triturating surfaces : in the two-toed Sloth, the two anterior teeth 

 of the upper jaw are longer and larger than the rest, and adapted 

 for piercing and tearing. In almost all the other Mammaha 

 particular teeth have special forms for special uses ; thus, the 

 front-teeth, from being commonly adapted to effect the first coarse 

 division of the food, have been called cutters or incisors, and 



