Practicad Course. aaAg. 91 
(N.B.—The following description of the internal anatomy is taken from 
immature specimens of the Rohita fish of Bengal. It will be found to 
apply in all important points to the Mahseer.) 
Pin the fish on to its side on the weighted bark, Slit the skin up 
the middle of the side, from the tail to the operculum, with scissors, 
dissect it away and pin it back. The powerful longitudinal muscles will 
now be exposed. Notice how they are split up into segments by trans- 
verse partitions. Notice also the large white cutaneous nerve which 
issues from beneath the operculum. 
Immerse the specimen in water and cut away the muscle on the 
ventral surface until the abdominal cavity is found, taking care not to 
cut into the organs which lie below. Then dissect off the whole of the 
muscles so as to expose the abdominal cavity completely throughout its 
entire length. Notice the dark-coloured membrane (peritoneum) with 
which the abdominal eavity is lined. A fold of this membrane supports 
the viscera. By moving the viscera about, without further dissection, 
the following organs can be made out :— 
(1) The exceedingly long and slender intestine, the coils of which 
occupy the greater portion of the ventral portion of the 
abdominal cavity In front the intestine passes into 4 
thicker tube (stomach), which is connected with the mouth 
by means of the gullet. Behind, it communicates with 
the anus, thus constituting a winding tube from one end 
of the body to the other. 
(2) In the front portion of the abdominal cavity the reddish 
glandular organ (liver), with large greenish gall bladder, 
communicating with the digestive tract below the 
stomach. 
(8) Dorsal to the’ digestive organs, the large transparent swim- 
bladder, which contains air. In full-grown carps, like the 
Rohita and Mahseer, the communication between the 
swim-bladder and the digestive tract is completely closed. 
(4) Dorsal to the swim-bladder, the large reddish kidney into 
which the dark-coloured distended caudal vein passes from 
behind. 
(5) The slender transparent duct (ureter) through which the secre~ 
tion of the kidney passes out behind the anus. This is a 
little difficult to see. 
Unravel the intestine with the help of fingers and scissors, Sketch 
the whole dissection. Then cut away the digestive tract and the lower 
part of the swim-bladder so as to clear the abdominal cavity and enable 
the kidney to be seen plainly. Dissect away the muscular wall between 
1 In the Mahseer the intestine is shorter and less slender. 
