. Mollusca ... Mollusks. PLECTOPXLIS. 139 Hah. Burma: Mergui {PTiilippi); Moulmain (StoUczJca, Theo- bald, Fea); 'N&ttonng (Theobald); 'Phu-thinz (Hungerford). The name Helix achatina having previously been employed (Potiez & Michaud, Galerie de Douai, i, 1838, p. 68), it is neces- sary to apply another designation to the shell hitherto knovcn as Plectopylis achatina, and I have much pleasure in associating with it the name of the naturalist who created the genus Plectopylis. The shell is sinistrorse, disk-shaped, very widely umbilicated, of various shades of chestnut, usually paler an
. Mollusca ... Mollusks. PLECTOPXLIS. 139 Hah. Burma: Mergui {PTiilippi); Moulmain (StoUczJca, Theo- bald, Fea); 'N&ttonng (Theobald); 'Phu-thinz (Hungerford). The name Helix achatina having previously been employed (Potiez & Michaud, Galerie de Douai, i, 1838, p. 68), it is neces- sary to apply another designation to the shell hitherto knovcn as Plectopylis achatina, and I have much pleasure in associating with it the name of the naturalist who created the genus Plectopylis. The shell is sinistrorse, disk-shaped, very widely umbilicated, of various shades of chestnut, usually paler and sometimes flammu- lated below, irregularly and finely striated. The apex is usually, but not invariably, raised slightly above the plane of the whorls. There are six or six and a half whorls, which increase gradually, and are more or less flattened above and tumid below; the first three and a half are smooth or nearly so, while the next two are. Fig. 70.—FUctopylis bensoni. somewhat coarsely striated and strongly decussated by spiral lines, less distinct on the upper side of the last whorl, obsolete at its side, but reappearing in the umbilical region. The last whorl is bluntly keeled above and subangulated at the periphery; this whorl suddenly widens at the aperture where it is deeply deflected. The aperture is almost horizontal, elliptic cordate, while the peristome is thickened and strongly reflected, livid or purplish-brown in colour, never luhite; the margins are united by a raised sinuous ridge, slightly notched at the junctions above and below. The parietal armature is of the same type as that of P. repercussa, but the lower arm of the bifurcation is the longer of the two (see fig. 70 c, which shows part of the parietal wall with the posterior portion of its armature), and the lower free hori- zontal fold close to the lower suture does not reach as far as the apertural ridge, and does not extend beyond the loiuer arm of the bifurcation and its posterior support. Fig.
Size: 1860px × 1343px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorg, bookcentury1900, bookdecade1900, booksubjectmollusks
