GASTRIC TEETH. 167 



on the two lateral edges of the upper jaw, which 

 is prolonged in the form of a snout (seen in a, 

 Fig. 293), obviously constituting a most formid- 

 able weapon of offence, b is a more enlarged 

 view of a portion of this instrument, seen from 

 the under side. 



§ 5 . Trituration of Food in Internal Cavities. 



The mechanical apparatus, provided for tritu- 

 rating the harder kinds of food, does not belong 

 exclusively to the mouth, or entrance into the 

 alimentary canal ; for in many animals we find 

 this office performed by interior organs. Among 

 the inferior classes, we meet with examples of 

 this conformation in the Crustacea, the Mollusca, 

 and above all in Insects. Thus there is found 

 in the stomach of the Lobster^ a cartilaginous 

 fame-work, in which are implanted hard cal- 

 careous bodies, having the 

 form, and performing the 

 functions of teeth. They 

 are delineated in Fig. 294, 

 which presents a view of 

 the interior of the sto- 

 mach of that animal . The 

 tooth A is situated in the 

 middle of this frame, has a rounded conical 

 shape, and is smaller than the others (b, c), 



