INTESTINE. 133 



rarely absent, and attached to the right lobe, or towards the 

 centre ; however, in some fishes it is detached from the liver 

 and connected with it by the cystic duct only. The bile may 

 be conveyed by one or more hepatic ducts into a common 

 duct which is continued towards the gall-bladder as ductus 

 cysticus, and towards the duodenum as ductus clioledochus; or 

 some of the hepatic ducts enter directly the gall-bladder, or 

 directly the duodenum, without communicating with the 

 common duct. Individual variations in this respect are of 

 common occurrence. 



A pancreas has been found hitherto in all Chondroptery- 

 gians, Acipenser, and many Teleosteans. In the first it is a 

 glandular mass of considerable size behind the stomach, close 

 to the spleen; its duct leads into the duodenum. In the 

 Sturgeons the pancreas is attached to the duodenum, and 

 opens close to the ductus choledochus. In Silurus glanis it 

 is very large, and the ductus choledochus passes through its 

 substance ; it is smaller in Belone and Pleuroncctes, and 

 situated in the mesentery ; its duct accompanies the terminal 

 portion of the ductus choledochus. In the Salmon, which 

 possesses a large lobed pancreas, the duct is so intimately 

 connected with the ductus choledochus that both appear 

 externally as a single duct only. 



The spleen, which is substantially a lymphatic gland, may 

 be mentioned here, as it is constantly situated in the imme- 

 diate vicinity of the stomach, generally near its cardiac portion. 

 With the exception of Branchiostoma, it is found in all fishes, 

 and appears as a rounded or oblong organ of dark-red colour. 

 In the Sharks frequently one or more smaller pieces are de- 

 tached from the principal body. In the Dipnoi a thin layer 

 of a very soft substance of brownish-black colour below the 

 mucous membrane of the stomach and upper part of the 

 intestine has been regarded as the homologue of the spleen 

 (Fig. 57, m). In most Teleostei the spleen is undivided, and 



