132 FISHES. 



and widtli, and whilst the narrowest serve only as secretory 

 organs, the widest are frequently found filled with the same 

 contents as the intestine. Wlien few in number, each opens 

 by a separate duct into the duodenum ; when their number is 

 greater two or more coalesce into a common duct ; in the 

 latter case the appendages cease to be free, and are connected 

 with one another by a more or less firm tissue. 



Coecal appendages at the end of the intestinal tract are of 

 exceedingly rare occurrence in fishes {Box). There is no 

 cloaca in Teleosteans. 



In the majority of Teleosteous fishes the vent is situated 

 on the boundary between trunk and tail, behind the ventral 

 fins. In a few it lies farther backwards, not far from the 

 caudal fin ; more frequently it is advanced forwards, under 

 the middle of the abdomen or to the scapular arch. In two 

 fishes, Aphrcdodcrus and AmUyopsis, it lies before the pec- 

 toral fins. 



A peritoneum envelops all the divisions ot the intestinal 

 tract within the abdominal cavity. A broad, well-developed 

 omentum has hitherto been found in Gobicsox cephalus 

 only. 



Liver. — The existence of a liver in Branchiostoma as a long 

 diverticulum of the intestine has been mentioned above. In 

 the Myxinoids the liver is divided into two glandular bodies, 

 an anterior rounded smaller one, and a posterior larger one of 

 an elongate shape. The gall-bladder Hes between both, and 

 receives a cystic duct from each of them. In the other fishes 

 the proportionally large liver is a single large gland, from 

 which only now and then smaU portions are found to be 

 detached. It is either simple, or with a right and left lobe, 

 or with a third lobe in the middle ; each lobe may have 

 incisions or subdivisions, which, however, are very inconstant. 

 The liver of fishes is distinguished by the great quantity of 

 fluid fat (oil) wliich it contains. The gall-bladder is but 



