316 



MOLLUSCA 



[CH. 



epithelium is folded and consists of tall cells which are actively 

 engaged in extracting excreta from the blood, as is shown by the 

 rows of granules with which they are filled. From the anterior ends 

 of the kidney two outgrowths project which immediately fuse into 

 one and constitute a great pouch called the dorsal sac (8, Fig. 144) 

 stretching upwards and backwards just underneath the shell. This 

 peculiar extension gives to the two kidneys the form of M, between 

 the median V and outer limbs of which lies the pericardium. 

 Posteriorly the cavities of the right and left kidneys also com- 

 municate with one another. 



-- 3 



FIG. 145. View of heart and chief blood-vessels of Sepia cultrata. 



Partly after Parker and Haswell. 

 1. Ventricle. 2. Auricle. 3. Ctenidium. 4. Anterior aorta. 5. 



terigraorta. 6. Anterior vena cava. 7. VeirTfrom ink-sac. 



B. (jreiillUl vein. 9. Branchial vein. 10. Branchial heart. 11. Eight 

 abdominal vein. 12. Vein from the mantle. 



The pericardium is a wide sac lying between the dorsal sac of 

 the kidneys and their ventral parts. At the sides it gives off the 

 reno-pericardial canals, whilst the stomach and intestine project 

 into its roof. 



The ventricle of the heart is a spindle-shaped sac lying trans- 

 versely (1, Fig. 145). Into its two ends open the tubular thin- walled 

 auricles which receive the blood from the ctenidia. From its 

 anterior wall a powerful artery, the anterior aorta, is given off 

 running forward above the oesophagus to the head, and a smaller 

 artery or posterior aorta goes backwards and upwards to supply the 



