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

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 attached to the neck, near the gills.)

 4. Gasteropoda, (with feet, or organs of motion,

 attached to the stomach.)

 5. Pteropoda, (with feet, or organs of motion,

 like wings.)

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The creatures belonging to this order, says Lamarck may be considered as the first vestiges of the appearance of a series of marine animals, intermediate in their formation between the fishes and the Cephalopods; they are all natives of hot climates, and possess a body of a jelly-like substance, and so transparent as to be seen with difficulty when floating in the water. They do not all possess shells, and are less known than they otherwise would be, on account of the great difficulty there is in preserving them.

This singular animal is rarely taken, on account of its delicate and perishable substance; it is found in the Southern Ocean. It will be seen, on referring to the engraving, that the shell which it bears merely covers a portion of its body, that in which the most material organs of the animal are found, namely, the heart and the branchiæ, or organs of breathing. These are most curiously placed on the upper part of its body, projecting from it and protected by a delicately white and transparent shell, shaped like a little cap, and of a substance resembling glass. The creature is able to enlarge its body by filling it with water, and in swimming the back is undermost. The shell, which seldom exceeds an inch in length, has been sought after by collectors with great assiduity, and has, at times, fetched as much as ten guineas at a sale; a perfect specimen is very rarely met with. There is a wax model of one of these shells in the British Museum, nearly two inches wide.