810 NATIC.E — THEIR FOOD. 



as Da Costa suspected,* and as Mr. Albany Hancock has 

 proved by his discovery of the composition of its prickles, 

 which are truly sharp siliceous teeth. " I found," he says ; 

 " this apparatus in Buccinum undatum to be composed of 

 rows of stout, much-curved spines or teeth, of great bril- 

 liancy, and as glossy and transparent as glass, and certainly 

 to have no appearance whatever of horny tissue. They are 

 so similar to those of Eolis, that there could be little doubt 

 that they are formed of the same material ; and accordingly, 

 after subjecting them to the action of acid, such was found 

 to be the case. Their capacity to drill holes in calcareous 

 matter, is therefore easily understood, without the necessity 

 of supposing the aid of a solvent requisite, as surmised by 

 Cuvier."-!- 



This anatomy of the proboscis is derived from an examina- 

 tion of the organ in Buccinum undatum, but it is applicable 

 to all the pectinibranchial or proboscidian Carnivora. The 

 other organs subservient to digestion in this tribe present 

 nothing remarkable in their organisation. The stomach 

 is a membranous bag, irregularly plaited on the inner sur- 

 face ; the intestinal canal, like that of carnivorous animals 

 in general, is short ; and the lower portion, or the rectum, 

 the inner coat of which is raised into several strong longitu- 

 dinal 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. 



The Naticas, — fine shells which live near the lowest 

 ebb of the tide, or within it, burrowing in the sand, or 

 in sand-banks far from shore, — are all carnivorous, and 

 also borers of other shells. Dr. Gould]; asserts that they 

 are very voracious, and play a conspicuous part in devouring 

 the dead fish and other animals which are thrown up by 

 the tide. The small circular holes with which bivalve shells 

 are often drilled, are the work of these snails, and made by 

 them to gain an entrance to the animal aj)parently so well 

 secured against such a foe. The foot can be expanded so 



* "And, if the holes, whicli are most commonly found in some species 

 of the Chamae, and the Screw Shells particularly, are examined with a glass, 

 they will be found to be so finely circular, that it is impossible to conceive 

 any menstruum should act upon it in so regular a manner." — Elem. of Con- 

 c/iulflgi/, 216. 



t Ann. and Mag. N. Hist. xv. 113. — The Purpura lapillus pierces the 

 common mussel in the same way, and by a similar instrument. — Ann. and 

 Mag. N. Hist. ser. 2, ii. 247. 



X Rep. Invertcb. Anim. Massachussetts, 232. 



