194 



TlIK VITAL FUNCTIONS. 



ing of the intestine not being in proportion to that 

 of the whole body, requires its being folded upon 

 itself for a certain extent. In the moth, (Fig. .328), 

 the contraction of the stomach has proceeded much 

 farther ; and an additional cavity, which may be 

 considered as a species of crop, or gizzard (o), is 

 developed : the small intestine takes a great many 

 turns during its course ; and a large pouch, or 

 ccBciim, has been formed at the part where it joins 

 the large intestine. 



The hepatic vessels are exceedingly numerous 

 in the Arachnida and Crustacea, occupying a very 

 large space in the general cavity ; and they com- 

 pose by their union an organ of considerable size, 

 bearing a greater resemblance in its form as well 

 as functions to the Liver of the higher classes of 

 animals. This organ acquires still greater size and 

 importance in the Mollusca ; where it frequently 

 envelopes the stomach, pouring the bile into its 

 cavity by numerous ducts.* As the structure and 



course of the intestinal canal va- 

 ries greatly in different tribes of 

 Mollusca, they do not admit of 

 being comprised in any general 

 description. The only examples I 

 think it necessary to give, in this 

 class, are those of the Patella, or 

 Limpet, and of the Pleurobran- 

 chus. The intestinal tube of the 

 Patella is delineated in Fig. .329 ; 

 where m is the mouth ; t, the 



* Transparent crystalline needles, the nature and uses of which 

 are quite unknown, are frequently found in the biliary ducts of this 

 class of animals. 



329 



