26 BRITISH MARINE TESTACEOUS MOLLUSCA : 
aid of the extraction of the vital principle. The mouth leads 
by a short cesophagus into the stomach, concerning which, 
the elastic stylet, and the tricuspid membrane or stomachal 
attritor, we refer to the account of the digestive organs of the 
Pholas dactylus. 
The food of the bivalves appears to be animalcule and soft 
crustacea. From the stomach, which is of suboval or pear- 
shape form, the intestine plunges obliquely to the lower part 
of the body, amidst the ovarium, and forms 2-5 or 6 convo- 
lutions, and at the last turn it ascends to the dorsal range, and, 
as rectum, discharges at the posterior extremity, either into an 
anal tube, as in the Pholades, Mye, &c., or without one, fixed 
externally or floating free, as in the Pectines and Anomie. 
The liver is usually a large, green, granular viscus, on the 
dorsal region, almost envelopmg the stomach, imto which it 
pours the bile by several ducts or orifices. 
The reproductive organs scarcely require mention, as they 
are largely noticed in the anatomy of the Pholas dactylus, 
above alluded to. We may, however, say, that all the bivalves 
are strict hermaphrodites without congression. The ovarium 
varies greatly in form and consistence at different seasons; im 
winter it has generally the aspect of homogeneity, but when 
under the stimulus of the genial months it becomes tumid, 
flaky or granular, and as fecundation advances the congeries 
of ova appear in progressive development until the term of 
gestation is complete, when they are ejected and deposited on 
various marine receptacles. These animals, though termed 
self-sufficient, have doubtless mixed up with their ovaria the 
male influences, which are apparently minute pear-shape bodies, 
only discoverable in the genial season, containing a glairy 
fluid, which may be to communicate the vital spark. In some 
genera, as Anodon, Mytilus, and a few others, the ova are 
deposited for a time amongst the network or mterspaces of 
the branchial laminze, in which they are further developed, and 
become testaceous, when they are finally ejected. 
In reference to the secretions already spoken of elsewhere, 
we will only observe that the mantle envelopes the entire 
animal; its edges are often ciliated, and the posterior end 
