CHAPTER III 

 THE TEETH OF INVERTEBRATES 



The teeth of this sub-kingdom present as many 

 variations and extraordinary forms as the or- 

 ganic designs of the heterogeneous mass of ani- 

 mals composing this great division. Not many 

 of these lower forms possess teeth, but when pres- 

 ent the form presented and the analogies sug- 

 gested are very instructive. They are analogous 

 to the teeth of Vertebrates, as the teeth are usually 

 oral organs in the Invertebrates and perform the 

 same functions as in the higher sub-kingdom, — 

 i.e., the prehension and reduction of food, pre- 

 paratory to digestion; but they are not homolo- 

 gous with the teeth of Vertebrates, however, as 

 they do not have the same origin or structure. 

 Almost every group, in some of its forms, ex- 

 hibits some sort of a dental apparatus for the 

 reduction of food, though few are homologous 

 with true teeth. Most of the lower forms are 

 without a masticating armature. 



Origin. The food-reducing mechanism of In- 

 vertebrates, whether oral organs or modified 

 limbs, is composed of calcified connective tissue 



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