Читать книгу The Book of Shells. Containing the Classes Mollusca, Conchifera, Cirrhipeda, Annulata, and Crustacea онлайн

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Lamarck says the observations of the habits of this creature tend to prove that, in addition to the power of completing its shell, as we have already noticed, it can, when its increased size has caused it to require a new habitation, desert its former shell and form a new one; from this it happens that the same individual can form successively many shells of different sizes, so that we find the same species both large and small.

When not in search of food, these animals are found buried in the sand, at some distance from the sea-shore, in temperate as well as in hot climates.

Family COLUMELLARIA.

This family is distinguished, from the next in having the columella plaited, and a notch at its base. It does not include any shells with a plaited columella, the opening at the base being entirely smooth, that is, without a notch.

The Diadem Whorl Shell is a very beautiful specimen of its genus; it is marbled with white upon a yellow ground, but the markings become nearly obliterated by age: it is as much as seven inches in length, and is found in the Asiatic seas. The head of the animal of this shell has two pointed tentaculæ, with an eye at the outer base of each. Its mouth is a lengthened cylindrical and retractile tube, furnished with little hooked teeth; it has also a tube to conduct the water to the branchiæ, springing out obliquely behind the head.