ON NAUTILUS AND SOME OTHER ORGANISMS. 173 
LON 
WAN 7 i 
es ie Z\ \ ASKEW SS aces 
ee to 
_— 
-— 
a> 
Fig. 18.—N. pompilius, ¢. Genital arteries from below. r. Rectum. 
r. a. Rectal artery. (N.B.—The rectal arteries are very variable.) aut. p. a. 
Anterior pallial artery. 7. 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.) 47. 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 gona- 
ducal artery, which supply the superjacent perigonoidal membrane. gez. a. 
Genital artery and its branches. ¢. Testis. ¢.0. Aperture of testis. p. v.0. 
Orifice of communication between the pericardial and visceral portions of 
body-cavity, through which the posterior pallial artery passes. goz. a. Gona- 
ducal artery. v.s. Vesicula seminalis. (N.B.—This structure, tlie testis and 
pear-shaped gland are closely united to the heart by a membrane.) J. v. 
Needhamian vesicle or spermatophore sac. #. Dotted line to indicate where 
the pallial duplicature merges into the body-wall ventrally. 
