of G aster op odous Mollusca. 407 
forwards and supported in the eentre of the cavity on a fleshy 
arch. When seen in the compressor, it is always doubled near 
the middle, as may be observed in Eolis under the same circum- 
stances. It is composed of ten or twelve plates or joints, each 
bearing a large crystalline spine, or rather process, apparently of 
a flattened or scoop-like form. These spines or processes are 
directed backwards to the oesophagus. In connexion with the 
anterior, or outer extremity of this prehensile organ, is placed 
what might be taken for an oval sac (figs. I c and 2 a), contain- 
ing spines, much resembling those of the tongue, but smaller. 
Professor Allman has pointed out in Actceon an appendage of the 
same kind, and supposes it to be a vesicle for the purpose of ge- 
nerating the spines of the tongue. In two or three species of 
the PolycerincBj as well as in some species of Doris, we have ob- 
served a similar organ, and have ascertained that in these species 
it is not a vesicle but a portion of the channel of the mouth, im- 
mediately in advance of the tongue, having the interior lined 
with rows of minute spines, forming, in fact, a prehensile collar, 
which on being everted forms a circle of curved spines, directed 
inwards, so as to lay hold of the food and carry it backwards to 
the tongue, which immediately conveys it to the oesophagus. In 
Actceon and Limapontia there can be little doubt that this sac- 
like appendage is an organ for the same purpose, though, on ac- 
count of the minuteness of the species we have examined, we 
should have found much difficulty respecting it but for the 
homology above alluded to. Be this, however, as it may ; judging 
from analogy, this sac-like appendage cannot be for the pur- 
pose assigned to it by Professor Allman, for the spines of the 
tongue are generated at the opposite extremity, as any one may 
convince himself by viewing the tongue of Purpura or Buccinum, 
when the spines will be observed at the inner extremity in a state 
of growth, apparently soft and not perfectly formed. 
Immediately in front of the buccal mass, and probably con- 
nected with the channel of the mouth, is a folliculated organ 
(fig. I d), which, perhaps, from its position and character, may be 
considered a salivary gland. 
The oesophagus (e) is a long, slender tube, passing from the 
posterior part of the buccal mass near the inner termination of 
tlie tongue, and ending about the centre of the body, where it 
dilates gradually into a stomach of no great size (/) ; but whose 
entire configuration we could not determine, having only seen its 
anterior portion, the rest being overlapped by the opake granular 
substance of the hepatic organ. 
The intestine {h) is short and slender ; it arises from the left 
side of the upper surface of tlie stomach, and, taking a sweep 
