ON NAUTILUS AND SOME OTHER ORGANISMS. 151 
at least, are displayed with a clearness which could be hardly 
attained by artificial injection. 
Fic. 2.—N. pompilius, ¢. View of dorsal surface of pallio-visceral 
region, to show the principal ramifications of the posterior pallial artery. 
m.e. Free mantle edge. ¢. Region of crop.  s.p. Siphuncular pedicle. 
1. Region of liver. s.a. Siphuncular artery arising from the right of the 
two main branches of posterior pallial artery. p.p.a. Posterior pallial 
artery. giz. Region of gizzard. g. Region of gonad. 7@ Region of 
intestine. 
N.B.—In front of siphuncular artery are seen two small branches which 
bend backwards and enter the siphuncular pedicle on its dorsal aspect. 
The pedicle is here represented turned forwards to expose its ventral 
surface. 
The mantle is simply riddled by these veins in a manner 
which defies one’s powers of draughtsmanship. The veins are 
collected into two main trunks, which le on either side of the 
anterior pallial artery, and proceed backwards to open into the 
afferent branchial vessels. At the sides of the mantle there 
are also a number of lateral pallial veins, which open into a 
large sinus situated over the shell muscle. 
