THE TEETH OF VERTEBRATES 55 



tional types. Thus the cones were duplicated 

 and tubercles added to form the multitubercu- 

 lar types. These molar tubercles are rounded 

 (Bunodont), as in Man, the Bears, Mastodon, etc.; 

 raised to form cutting blades in the carnivora ; or 

 folded and duplicated (Lophodont) in the herbiv- 

 orous mammalia to form broad triturating sur- 

 faces, etc. 



The Number of the Teeth in Vertebrates varies 

 greatly in different classes, and may even vary in 

 the same genera. Some fishes are entirely with- 

 out teeth of any kind; others have but one (as the 

 Myxine and other parasitic forms), which is used 

 as a lancet to cut the flesh for the purpose of 

 drawing blood; others have a few teeth, and the 

 number increases up to the thousands, in the bony 

 fishes, and which may stud the mouth in every 

 conceivable position. These are of continuous 

 succession, so that the numbers are always indefi- 

 nite. The reptiles have fewer teeth than the 

 fishes, but these succeed one another continuously, 

 and the exact number cannot always be deter- 

 mined. Different individuals of the same species 

 will present great variations. In the mammals 

 the number can be determined with greater preci- 

 sion, as each species, especially of the higher 

 forms, has a definite number. In the lower mam- 

 mals, as with the reptiles, the number is somewhat 

 indefinite, but with the advance in the scale it be- 



