Proceedings of the Bristol Naturalists' Society. New ser. Vol. 3 (1868)-v. 4 (1869).

  • Bristol Naturalists' Society.
Date:
1868-1870
Catalogue details

Licence: Public Domain Mark

Credit: Proceedings of the Bristol Naturalists' Society. New ser. Vol. 3 (1868)-v. 4 (1869). Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    mamimiform spire, and the unsymmetrical finish, or more correctly commencement of the suture, give the shell an awkward appearance. The whelk requires two or three seasons to attain maturity, and certainly lives six yea-is, probably more, for I have obtained, from the deep water outside the Dogger-bank off Scarborough, full-grown living specimens of the large variety “pelagica ” with four-year-old oysters attached to the last or largest volution. The arrangement of the sexes in the mollusca is very interesting The terres- trial gasteropoda (such as the garden snail) are monoecious, each individual possessing both sexes, yet incapable of self-fertilization. Some of the fresh-water gasteropoda, as “ Valvata,” change their sex, first be ng male and afterwards fe- male, and are capable of self-fertilization; whilst the whelk, and probably all marine gasteropoda, are dioecious, each individual being of one distinct and unalterable sex. The male whelk has a longer and slenderer shell than the fe- male ; the sex, however, cannot be determined by the shell. The proboscis of the whelk is singular and interesting. It is a long conical and retractile member, which can be protruded two or more inches beyond the snout, or retracted into a chamber which is situated on the upper part or back of the animal. The length of the chamber is not one-half that of the proboscis it receives. At its base the proboscis is attached to the anterior part of the chamber^ from the sides and posterior part of which a number of muscular fibres radiate, having the other extremities attached to the inside of the proboscis. The contrac- tion of these fibres draws the anterior part of the proboscis within the posterior part, in very much the same manner that a stocking is doubled back upon itself. By means of this highly ingenious piece of mechanism the space required for the reception of the proboscis is reduced one-half. Within this muscular sheath or proboscis is the lingual ribbon or tongue, which has lately received the name of “odontophoreUpon it, most beautifully and regularly arranged, are numerous hard and pointed teeth, and, like all the odontophores of the gasteropoda, it is a very interesting object for microscopical investigation. Some systematists assert that the odontophore affords sure evidence of, not only specific and generic, but also of family distinctions. Professor Stimpson has lately raised Nassa from being a genus in the Buccinid® to the type of a distinct family, which he calls Nassidse (which includes the genus Columbella), solely on odontologial grounds, namely, the arched form and very numerous denticles of the rachidian tooth.” B.—Geological development. Buccinum undatum first made its appearance during the epoch of the Coralline Crag, and is therefore geologically speaking a creature of yesterday. Since that epoch down to the present time it has become more and more abundant, arid is now one of our commonest shells, living in countless millions in all our seas. 2nd—Its Habits. The whelk is a carnivorous predatory creature. Crawling over the sea bottom in search of dead fish or mollusca, it performs the duties of a scavenger. Having found a living mollusk (it seems to prefer a bivalve) it seizes it with its ample foot and by a semi-rotatory motion of the proboscis, in which is the armed tongue previously described, it drills a holo through the shell, killing and afterwards devouring the inhabitant. The length of time occupied in doing this of course depends entirely on the thickness of the shell operated