298 



APPENDIX III 



into the body, where it flows up between the membrane of 

 the intestinal sinus and the body wall, bathing the muscula- 

 ture in its course. It is interesting to note that a special 

 separate stream flows from each limb into the cardial sinus, 

 there being membranous dissepiments, corresponding with 



ao 



FIG. 67. Diagram of the circulation from above. '7i, heart, expanded by the fine 

 connective tissue ala; () ; s, segmental septa forming the transverse walls of 

 the dermo-muscular sinuses (Is) ; ac, cephalic aorta ; g, lateral artery to shell 

 and shell gland ; /, points of attachment of dorso-ventral muscle bands to dorsal 

 wall. 



the segmental constrictions, stretched between the body wall 

 and the membrane of the intestinal sinus. The dissepi- 

 ments, which have already been described in the text, are 

 only formed in the first ten to eleven segments, i.e. as 

 far as the heart extends. Thus while part of the blood, 

 flowing through the intestinal sinus, passes down through 



