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 Clarn, 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 Mollnsks, 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 body, usually on the right 

 side. 



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

 exhibit a marked advance. A mouth with powerful man- 

 dibles 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 opena 

 into the "funnel" 

 near the mouth. 



Fishes have a 

 simple, short, and 

 wide alimentary 

 canal. The stom- 

 ach is separated 



Pto. 44. Alinientiiry Caunl of the Oyster: a, Btomnch f pom the intestine 

 laid open ; ei, liver ; 6, c, d,f, convolutions of the intes- 

 tine , (7, anal apertnre; n, o, auricle and ventricle; /, by a nari'OVV " py- 

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

 show the venous canals ut the base of the gills. lOHC OrmCC, or 



