REPRODUCTIVE ORGANS AND GENITAL ARTERIES. 



785 



their way to the exterior. I say virtually, because the coelomic aperture of the gonadic 

 pouch becomes, in the adult, so closely approximated to the coelomic orifice of the genital 



Fig. 10. N. pompilius, a . Genital arteries from below, r. rectum ; r.a. rectal artery. (N.B. — The rectal 

 arteries are very variable.) ant.p.a. anterior pallial artery; i.a. intestinal artery. (N.B. — This artery 

 usually passes to the right of the rectum, as shown in this figure ; but in one instance I have observed 

 it to pass down to the left of the rectum.) In-. v. branchial veins; post.p.a. posterior pallial artery; 

 p.s.g. pear-shaped gland with its artery; a. branches of the preceding artery and of the gonaducal artery, 

 which supply the superjacent ligaments; gen.a. genital artery and its branches; t. testis; t.o. aperture 

 of testis; p.v.o. orifice of communication between the pericardial and visceral portions of body-cavity, 

 through which the posterior pallial artery passes ; gmi.a. gonaducal artery ; v.s. vesicula seminalis. 

 (N.B. — This structure, the testis and pear-shaped gland are closely united to the heart by a ligament.) 

 N.o. Needhamian vesicle ; x. dotted line to indicate where the pallial duplicature merges into the body- 

 wall ventrally. [From Quart. J. Micr. Sc. Vol. 39, 1896.] 



duct, often actually penetrating into the latter though separate from it, that the ova 

 and spermatozoa are conveyed directly from the gonad to the duct. 



The main trunk of the median genital artery applies itself at first to the dorsal 

 side of the gonad, and extends round to the ventral side, giving off branches of greater 

 and of lesser importance. 



In the female the ultimate ramifications of the genital artery reach the surface of 

 the individual ova, the finer branches following but not confined to the reticulations 

 formed by the ridges of the follicle which project into the yolk (PI. LXXXIII. fig. 17). 

 The arteries which traverse the surface of the ova (PL LXXXIII. figg. 15 and 16), give 



