2 30 Records oj the Indian Museum. [Vol. XXII^ 



expansion of the body muscle meets the mantle margin. The 

 main hepatic artery is continued upwards between the liver and 

 stomach, where we have already noticed it l3'ing in the longitu- 

 dinal fold on the posterior wall of the cardiac portion of the 

 stomach, and ends in branches suppl3-ing the liver in the apical 

 whorls. 



The venous system consists very largely of wide spaces or 

 sinuses, whose walls are very thin and in consequence are very 

 difficult to define. Occupying the central portion of the foot, between 

 the dense white muscle and the grey spongy tissue of the sole, 

 is a wide irregular sinus, the blood from which, according to Ley dig, 

 passes upwards and backwards to reach the venous sinus on the 

 ventral posterior aspect of the kidney. This sinus appears to 

 be joined at the left posterior angle of the kidney by a venous 

 sinus, which runs up the right side of the branchial fold in the 

 floor of the mantle cavity, and it is also joined by a sinus crossing 

 from right to left along the posterior and upper margin of the 

 kidney and having its origin in the perirectal sinus. The con- 

 joined vessel passes down superficially on the left side of the 

 kidney between it and the branchial gland. This vessel is known 

 as the afferent gili-veiu. Lying to the right of the kidney in the 

 body-wall is a large sinus which receives blood from the organs 

 lying in the upper coils of the visceral hump ; this passes down- 

 wards and at the apex of the kidney joins the afferent gill-vein 

 that we have already seen passing down the left margin along the 

 branchial gland. The afferent gill-vein can be traced down the 

 whole length of the branchial gland on the right of the gill-base 

 almost as far as the mantle margin ; below the level of the kidney 

 it is joined by a further series of small branches which arise from 

 the perirectal sinus and pass across the thin median portion of the 

 mantle roof. The perirectal sinus also received tributaries in the 

 female from the wall of the uterus. The afferent gill-vein supplies 

 branches to the gill-filaments and the blood after being aerated 

 returns to the efferent gill-vein which lies on the left side of the 

 base of the gill ; this vein passes from below upwards and at the 

 apex of the mantle cavity opens into the cavity of the auricle. 

 A large vein runs down beneath the floor of the branchial chamber 

 on the right side of the oesophagus. Superiorly it receives tributaries 

 from the liver, and in the 9 from the albumen gland and egg-shell 

 gland while a large branch passes up on the inner aspect of the 

 uterus and then crosses over behind the sub-intestinal nerve to join 

 it near the apex of the branchial cavity. 



The Renal System. 



The kidney is a triangular pyramidal organ of a pale greenish 

 colour, lying in the roof of the mantle cavity at its extreme apex. 

 Along the external or right margin runs the rectum and the peri- 

 rectal blood sinus, below which lies the commencement of the 

 ureter, while along the left or inner margin is the commencement 

 of the afferent gill-vein and the base of the gill. The posterior 



