New illustrated natural history of the world / by Ernest Protheroe ... with 24 coloured plates (73 figures) and nearly 300 photographs direct from nature chiefly by W.S. Berridge.

  • Ernest Protheroe
Date:
[1910]
Catalogue details

Licence: In copyright

Credit: New illustrated natural history of the world / by Ernest Protheroe ... with 24 coloured plates (73 figures) and nearly 300 photographs direct from nature chiefly by W.S. Berridge. Source: Wellcome Collection.

    558/639 (page 487)
    THE GASTROPODS The Gastropods form an enormously large order, for they com- ] prise the snails, whether terrestrial, aquatic or marine, the whelks, limpets, etc. The shells vary in shape ; the majority are external and spirally Gvisted, but some are tubular, or conical; some of the creatures have internal shells, and others have no shell of any kind. Many of the shells exhibit the most brilliant coloration, and are ■ employed in the manufacture of beautiful cameos. In size they : range from those of quite minute proportions to those that can ibe used as signal horns, for baling out boats, or as water vessels ig:enerally. The Gastropods are nearly all crawlers, making progress •by the expansion or contraction of the muscular foot. The head is 'usually more or less distinct. The teeth are very variable in form, .and still more in number ; some species have thousands of minute Teeth, set chiefly on the tongue, not for biting, but for rasping even liard substances. One structure belonging to most of these creatures :must not go unnoticed, viz., the ‘ operculum,’ which closes the . aperture of the shell when its owner is withdrawn into the recesses of its home. An examination of the water-snail will show that the operculum is composed of a horny substance’, thicker and heavier tthan any other portion of the mantle. The Whelk [Buccinum undatum) is one of the most carnivorous ■ of the molluscs. Its long tongue, armed with row upon row of (Curved and sharp-edged teeth, harder than the notches of a file .and keen as the edges of a lancet, is a most irresistible instrument •when rightly applied, drilling a circular hole through the thickest i-shells as easily as a carpenter’s centre-bit works its way through a (deal board. Vast quantities of Whelks are taken in large wicker (baskets, which are baited with the refuse portions of fish and i lowered to the bottom of the sea by ropes. The eggs of the Whelk ;are little yellowish capsules, each of which contains several minute >shells. When the young are hatched the capsule splits at one tend, so as to allow the escape of the tiny creatures. The Periwinkle [Littorina littorea) belongs to a family of shore imolluscs that frequent the coasts and feed upon various algae, sscraping away the vegetable matter with a formidable series of >sharp teeth. Numerous shells, such as cones, volutes, harp-shells, olives, and imitres always figure largely in the collections of conchologists, itheir shapes being indicated by their names. The Scorpion-shell [{Pteroceras aurantias) is creamy white on the exterior and rich • orange within. The curved spines are white and shiny. This f.gastropod is not a crawler, but a hopper, to assist which the foot iis particularly muscular. The Cowry [Cyfrea moneta), yellowish mr white in colour, with grooved or wrinkled edges of the lip, is of