380 ZOOLOGY. 



Their excretory ducts terminate in a kind of bladder, the 

 external orifice of which is situated immediately behind the 

 anus and the orifice of the reproductory organs. 



Digestion seems to be performed rapidly, and the chyle is 

 absorbed by numerous lymphatic vessels which terminate by 

 several trunks in the venous system near the heart. 



Fig. 389. The Turbot. 



487. The blood of fishes is red, and the globules are 

 elliptic, and of considerable size ( 81, Fig. 37 c). The heart 

 (Fig. 52) is placed under the throat, in a cavity separated 

 from the abdomen by a kind of diaphragm protected by the 

 pharyngeal bones, the branchial arches, and the humeral 

 girdle. It is composed of an auricle and ventricle, from which 



Fig. 390 Head of the Shark. 



springs the pulmonary artery. This vessel is enlarged into a 

 contractile bulb at its commencement ; it soon divides into 

 branches, which proceed to the gills ; and the blood, after 

 having traversed these organs, returns towards the heart by 

 another vessel, also passing along the edge of the branchial 



