232 THE DOG-FISH 



the cceliac artery. It supplies the intestine 

 and rectum, and gives branches to the genital 

 organs. 



iv. The lieno -gastric artery is a median vessel 

 arising from the aorta immediately behind the 

 mesenteric artery. It supplies the loop of 

 the stomach between its proximal and distal 

 limbs, and also the spleen and part of the 

 pancreas. 



v. The inferior mesenteric artery is a small median 

 vessel arising from the aorta about an inch 

 and a half behind the lieno -gastric, and running 

 backwards in the mesentery to the rectal 

 gland, which it supplies. 



vi. The parietal arteries are small paired vessels 

 arising at intervals along the whole length of 

 the aorta, and supplying the body-walls. 



vii. The renal arteries are small paired vessels 

 arising from the aorta along the greater part 

 of its length, and supplying the kidneys, which 

 they enter from the dorsal surface. 



To see the renal arteries, dissect one kidney away from the 

 body-wall and turn it inwards, so as to expose its dorsal surface. 



viii. The iliac arteries are a pair of small vessels 

 leaving the aorta near the hinder end of the 

 body-cavity, and running outwards in the body- 

 walls to the pelvic fins, which they supply. 



D. Dissection of the Heart. 



Remove the floor of the mouth, with the heart and peri- 

 cardium. Pin it down in a dish under water, with the ventral 

 surface upwards. Open and examine the several cavities of 

 the heart in the order given below, washing out the contained 

 blood by a stream of water. 



Open the ventricle by a horizontal incision, and continue 

 the cut forwards along the right side of the conus arteriosus 

 to its anterior end'. Turn the ventral portions of both ventricle 

 and conus over to the left side. 



