. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FUNCTION OF VARICES 63 Morphometry The following morphometric measurements on perfect, uneroded shells were made: areas of the three main varices and left-remnant varix (described below), aperture area, aperture length, total shell length including siphon, labial spine (tooth) length, and live body weight (measured in air with the animal retracted into its shell). The left-remnant varix constitutes a remnant of the pre- vious left varix that abuts on the current right varix to form a combined right-sh
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FUNCTION OF VARICES 63 Morphometry The following morphometric measurements on perfect, uneroded shells were made: areas of the three main varices and left-remnant varix (described below), aperture area, aperture length, total shell length including siphon, labial spine (tooth) length, and live body weight (measured in air with the animal retracted into its shell). The left-remnant varix constitutes a remnant of the pre- vious left varix that abuts on the current right varix to form a combined right-shelf area of larger dimension (see Fig. 1, bottom). This abutment is often not perfect, yet visual analysis of many shells suggests that the animal may use this remnant as a guide to where to terminate growth of each new varix. The end result of the juxta- position of these two varices. and the surface area of the left varix, is a broad shelf surrounding the aperture. The labial spine projects downward from the anterior- right aperture margin. It is an extension of a shallow collar that borders the aperture on the right-hand side. It is this collar that ultimately extends during growth to form the new right varix. and the spine remnant can be seen embedded in the upper surface of each preceding varix. Its function may be to anchor the snail during feeding, as surmised for other gastropods (Paine, 1966). Spine length was denned as the magnitude of its extension above the rim of the collar. Varix and aperture areas were determined by drawing their outlines at 8-power magnification using a Leitz drawing tube, then analyzing with a SIGMA-SCAN area- measurement software system (Jandel Scientific, Cali- fornia). Allometric or isometric relationships between the mor- phological features were investigated with standard least- squares linear regressions calculated on log-transformed values for several combinations of variables. The slope (/>) of a regression is often underestimated du
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
