88 Invertebrate Zoology. 



Each of the spermatozoa, or male-cells, will be found to 

 consist of a somewhat cylindrical body, which is terminated 

 at one end by a series of long spines. 



Make a drawing of one of the testes as seen from the side, 

 representing the vas deferens, and the external opening. 



The Circulatory System. The position of the heart 

 has been already noted. In a specimen having the circula- 

 tory system artificially injected with a colored fluid, note the 

 pericardial sac, a delicate tissue surrounding the heart. It 

 receives the blood from the branchitzf which then enters 

 the heart through six cardiac apertures. The dorsal, lateral, 

 and ventral apertures occupy positions as suggested by their 

 names. 



The origins of the arteries, as they leave the heart, are as 

 follows : 



The superior abdominal artery passes directly posteriorly 

 from the heart, resting on the sexual organs, intestine, and 

 deeper muscles. How many branches does it give off to 

 each abdominal segment? Does it send branches to the 

 sexual organs? Intestine? Caecum? Note any terminal 

 bifurcation. 



The sternal artery has its origin from the most anterior 

 point of the superior abdominal artery. It passes ventrally 

 to supply the lower portions of the body. On which side 

 of the intestine does it pass? 



The ophthalmic artery runs from the heart anteriorly. 

 Does it give off branches to the stomach ? Can you deter- 

 mine its distribution in the anterior part of the head ? 



The antennary arteries arise from near the antero-lateral 



1 Later dissection will show that the blood is returned from the 

 branchice through six branchio- cardiac canals. 



