212 



FISHES 



The gullet opens into the stomach, which consists of an 

 anterior i-egion that extends straight back and ends blindly; 

 a posterior region that leaves the anterior i-egion at right 

 angles near its middle; and three long, cylindrical, blind 

 sacs, the creca (Fig. 148). The intestine begins just back 

 of the ca^ca and after one or two turns terminates at the 

 anal opening. Tlie liver lies in the anterior end of the body 

 cavity antl has on its posterior surface a gall bladder which 

 empties its bile through a short duct into the anterior part 

 of the intestine. 



Circulatory system. — The heart of the perch lies between 

 the gills and is in close relation to them. It is inclosed in 



Efferent qill aHeiie-s Hjpatie_artery 



Caudalarlery 

 Caudaiveln 



Heart 



Kidney 



^_ OvaTT/ 



^___ 'AlbmenUert/ canal 



Hepatic vein Liver Mesenteric arterT^ 



VlG. 140. — Circulation of a fisli. 



the pcricai ( ii.'> I cavity wliich is entirely separate from the 

 main bo(fy cavity. Tlie heart consists of three ]3arts, the 

 siniiK veunsii.s, the thin-walled auricle, antl the nmscular 

 rcntriclc, placed in the order named, beginning at the 

 posterior c'nd. The A'cntricle pumps the blood from its 

 anterior end through a large artery that sends a branch to 

 the lower end of each gill. The blood then flows upward 

 through the gill filaments and leaves them from the dorsal 

 ends tliKiugh aiiciics tliat finally meet in the median plane 

 on Q\r, (|(,rsal side of the body cavity and form the doisal 



