ON MOLLUSCA. 213 
while the second, which has more resemblance to the ceeliac 
tripod, sends its ramifications to the stomach, to the rest of 
the intestine, to the liver, and to the secretory organs of ge- 
neration. 
In the acephalous mollusca the circulatory apparatus pre- 
sents some differences from that of the cephalous. ‘The veins 
of each gill are united in a lateral auricle, placed on each 
side, and after a contraction often very sensible, each of the 
two auricles opens into a ventricle, which is situated in the 
medio-dorsal line. ‘This ventricle is usually fusiform ; but 
what it exhibits most remarkable is, that it appears to be 
traversed by the rectum, because, in its breadth it recurves 
around this intestine, so that the two extremities of its trans- 
verse diameter appear to touch. From the root of this ven- 
tricle spring two aortz: a posterior one, smaller, which passes 
under the rectum, and gives out branches to the posterior 
parts of the body, and an anterior much more considerable, 
which proceeds as far as the anterior adductor muscle, fur- 
nishes branches to the stomach, to the liver, to the foot, and 
to the other surrounding parts, recurves below by an anas- 
tomosing branch, which follows the edge of the mantle, to 
unite itself to a similar branch of the posterior aorta, and 
forms a large arch, of which the lower branches go to the 
tentacula of the edge of the mantle, while the others, more 
considerable, remount and distribute themselves to all its 
parts. 
The venous radicles of the belly, and of all the anterior 
parts of the body, unite in two gross trunks, which proceed 
from the hepatic region below the rectum, and after having 
received, by many radicles, two veins, which have followed the 
edge of each lobe of the mantle, they open at the anterior ex- 
tremity of a sort of auricle or venous reservoir, placed longi- 
tudinally under the heart in the dorsal line. This reservoir 
receives by its posterior extremity two other veins, tolerably 
