41^ Natural History of Molluscous Animals : — «• 



canals {jy)i and the greater portion of the gullet (gg) : 

 the tongue is a very narrow cartilaginous membrane, armed 

 with numerous acute spines or prickles curved backwards ; 

 and the principal purpose of the elongation of the proboscis 

 is seemingly to carry its rough point to the body which the 

 snail wishes to perforate and suck. (Cuvier, Mem, sur les 

 Mollusq. M., xvii. 7.) 



This anatomy of the proboscis is derived from an exami- 

 nation of the organ in Succinum undatum, but it is appli- 

 cable to all the pectinibranchial or proboscidian Carnivora. 

 The other organs subservient to digestion in this tribe pre- 

 sent nothing remarkable in their organisation. The stomach 

 is a membranous bag, irregularly plaited on the inner surface ; 

 the intestinal canal, like that of carnivorous animals in ge- 

 neral, is short, and the lower portion, or the rectum, the 

 inner coat of which is raised into several strong longitudinal 

 folds, is wide, and opens on the right side of the branchial 

 cavity under the margin of the collar. Cuvier observes that 

 the sides of the rectum are thickened by a whitish substance, 

 fatty, and a little granular, of which the use is unknown. 



It appears to be ascertained that the Bullae are also feeders 

 on the Bivalved MoUusca. Mr. Humphreys mentions that 

 he had found a species of 3iya alive in the gizzard of 

 Bulla lignaria. {Lin. Trans., ii. 16.) Cuvier says that the 

 stomach of the Bullae, in general, is usually filled with the 

 remains of small shells [Mem, sur les MoUus. M., x. 14.) ; 

 and Mr. Sowerby tells us that they are " exceedingly vora- 

 cious, as is evident from the fact, that the animal of B. aperta 

 is sometimes distorted by having swallowed entire a Corbula 

 nucleus, which is a very thick and strong shell, nearly equal 

 in size to itself." {Ge7i, Bee, Foss. Shells, No. 39.) Now, as 

 the Bullae have no perforating instrument in the mouth, nor 

 jaws to crack them, they are under the necessity of swallow- 

 ing their prey entire, and, as might have been anticipated, 

 there is provided an internal apparatus to supply this defi- 

 ciency, and break up the shells, so that the inmates may be 

 exposed to the influence of the digestive agents. This singular 

 apparatus is placed within the gizzard, and consists of three 

 strong calcareous pieces, differing in form and size in the 

 different species, thus modified, undoubtedly, to suit them to 

 their peculiar wants, and moved by powerful muscles against 

 each other.* In the Aplysia, a genus of the same natural 



* Cuv. Mcm.y X. 13. These stomachal teeth were described by Gioeni 

 as a new genus of multivalve shells ; a genus retained by Retzius, Bruguiere, 

 and Lamarck, until the mistake was detected by Draparnaud. (See Bosc, 

 Vers., i. 76.) 



