80 



COMPARATIVE ZOOLOGY. 



the intestines end in a large bladder-like expansion. Scor- 

 pions have no stomachal cavity a straight intestine passes 

 directly through the body. 



In bivalve Mollusks, like the Clam, the month opens 

 into a short oesophagus which leads into the stomach, 

 which lies imbedded in a large liver, and the intestine, 

 describing a few turns, passes directly through the heart. 40 

 In the univalve Molhisks, like the Snail, the gullet is long, 

 and frequently expands into a crop ; the stomach is often 

 double, the anterior being a gizzard provided with teeth 

 for mastication ; the intestine passes through the liver, 

 and ends in the fore-part of the bod} 7 , usually on the right 

 side. 



, The highest Mollusks, as the Cuttle-fish and Nautilus, 

 exhibit a marked advance. A mouth with powerful man- 

 dibies leads to a long gullet, which ends in a strong mus- 

 cular gizzard resembling that of a fowl. 41 Below this is a 

 cavity, which is either a stomach or duodenum ; it receives 



the bile from a 

 large liver. The 

 intestine is a tube 

 of uniform size, 

 which, after one or 

 two slight curves, 

 bends up,and opens 

 into the "funnel" 

 near the mouth. 



Fishes have a 

 simple, short, and 

 wide alimentary 

 canal. The stom- 

 ach is separated 



FIG. 44. Alimentary Caunl of the Oyster: a, stomach f rorn the intestine 

 laid open ; d, liver ; b, c, d,f, convolutions of the intes- 

 tine ; g, anal aperture; n, o, auricle and ventricle; I, by a narrOW " PY~ 

 m, adductor muscle; h, k, lobes of month divided to , . . 

 show the venous canals at the base of the gills. lOHC Orince, Or 



