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

17 страница из 32

ssss1

The Trachelipodes contain by far the largest portion of the univalve shells, and are mostly inhabitants of the waters. They form two numerous groups, the feeders on animal food, (Zoophagi,) and those that exist on vegetable substances, (Phytophagi.) The animal feeders are well distinguished from the other group, by having a mouth without jaws, being furnished with a tube which they can retract or advance at pleasure, for the purpose of sucking their nutriment from the bodies of other inhabitants of the deep. The animal feeders are also known from the other section by the possession of a projecting tube called a siphon, which conveys the water to the gills. The shell also points out to which section its possessor belonged, from the lower part of its opening being formed either into a sort of canal, or a groove for the reception of its siphon. They are all marine animals, and breathe water. The flesh-eating tribes compose five families.

 Family Convoluta, (rolled up like a scroll.)