of Gasteropodous Mollusca. 407 



forwards and supported in the centre 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. 1 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 Polycerince, 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. 1 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 

 the 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 the stomach, and, taking a sweep 



