in the Fish Gallery of the Indian Museum. 25 



The pancreas and spleen are left in their natural 

 position, but the liver, which is a large oily organ that 

 fills a large part of the abdominal cavity, has been 

 removed. 



The mouth of Fishes is generally large, and teeth are generally present 

 not only in the jaws, but often also on several bones of the palate, and even 

 on the tongue and on parts of the branchial arches. It would almost need a 

 special gallery to exhibit the various forms of teeth that are found among 

 Fishes : they all, however, agree in being impermanent structures that are 

 shed and replaced throughout the life of the animal, and in being more 

 usually fixed to the bone than sunk in sockets ; and although in certain Fishes 

 that feed on hard substances such as mollusks and living coral they are 

 adapted for crushing, they are never organs of mastication, but are merely 

 used for prehension, — for the majority of fishes are predaceous and bolt their 

 prey whole. 



The gullet is short and wide, and the stomach is large and capable of 

 enormous distension, especially among the highly predaceous deep-sea fishes, 

 some of which can swallow prey actually larger than themselves. 



The general nature of the BREATHING-ORGANS and 

 Heart in Fishes is illustrated by dissections of a Ruhu 

 [Labeo) and of a Sting-ray (Trygon) in Case 10, in which 

 the pericardial cavity that contains the heart has been 

 opened, and the main arteries and the gills have also 

 been laid bare. 



In both these fishes the breathing-organs, or gills, 

 consist of rows of leaf-like vascular folds of mucous 

 membrane, attached to the branchial arches like the 

 barbs of a feather, in which the blood gets rid of its 

 gaseous impurities and absorbs Oxygen from the sur- 

 rounding water. 



In both, also, the heart lies immediately behind the 

 gills and consists, from behind forwards, of the following 

 parts: (1) a thin walled venous sinus, into which the 

 4 



