THE TEETH OF EEPTILES 99 



The Alleghany Mempomona is a typical Sala- 

 mander. There is a groove upon the edge of each 

 jaw, in which the teeth rest by an enlarged base 

 on the bottom and the points just rise above the 

 margins of the groove. The teeth number sixty 

 to eighty in each jaw; are about equal in size, 

 sharp-pointed and recurved. They are attached 

 by ankylosis to the outer walls of the groove, — a 

 method of attachment called "Pleurodont," be- 

 cause of its resemblance to the attachment of the 

 ribs. 



The Axolotl — a peculiar Mexican lizard with 

 permanent gills — has rasp-like teeth, of a fish-like 

 character. The Proteus also has permanent gills. 

 It has sharp, fine teeth in front and a horny palate 

 behind. The teeth of some extinct Batrachians 

 whose remains have been preserved in the rocks 

 present some remarkable features. The Laby- 

 rinthodont form was so named on account of the 

 extraordinary folding of the dental tissues, which 

 were longitudinally crimped so that in a section 

 of the tooth it looks like a roll of pleated and 

 crushed cloth. The pulp-cavity was subdivided 

 into a number of radiating branches which 

 reached out into the folds. 



The teeth of the true Reptiles, with few ex- 

 ceptions, present simple conical forms with more 

 or less sharp points, which vary in length and are 

 circular or oval on section. The teeth are long 



