Image from page 188 of "Introduction to zoology; a guide to the study of animals, for the use of secondary schools;" (1900) (14762026306)

Identifier: introductiontozo00dave
Title: Introduction to zoology; a guide to the study of animals, for the use of secondary schools;
Year: 1900 (1900s)
Authors: Davenport, Charles Benedict, 1866-1944 Davenport, Gertrude Anna Crotty, 1866-
Subjects: Zoology
Publisher: New York, Macmillan company London, Macmillian and co., ltd.
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library



Text Appearing Before Image:
oyster drill. It bores through the FIG. 158 - -Urosal- J pinx, the oyster shell of this and other bivalves bv means */ of its radula and sucks out the contentsthrough the hole. Crepidula,2 the boat shell or decker, represents atype in which the spire has become almost obsolete. It is drill. Nat. size.Photo, by W. H.C. P.
Text Appearing After Image:
FIG. 15U. — Crepidula, the boat shell. Two-thirds nat. size. Photo, by W. H. C. P. still represented, however, in a rudimentary way at the leftof the aperture (Fig. 159). The modified shape is associatedwith the habit the mollusk has of lying, aperture down- 1 ovpd, tail; adXiriy^ a trumpet. - A small sandal (crepidcC). 170 ZOOLOGY ve sh m.e ~nu mu ward, close to the rock or another shell. By this meansthe animal is better protected. The deck is a plate which has been de-veloped internally tohelp hold the animalin the shell. The limpets aremodified prosobranchs.They are bilaterallysymmetrical, and arecovered by a flat, coni-cal shell, which is ap-plied closely to the rockall around the base insuch a way as to pro-tect the animal within.In some species (genus _ * ISSUrella a) there IS an lamellse; m.e, edge of the mantle; mu, at- opening at the apex oftachment muscle; si, slits in the attachment muscle; sh, shell; v, efferent branchial the shell through whichvessel; V aorta -,ve .sma