OCR Text |
Show 1878.] FROM JAPAN AND BORNEO. 497 oblique thread-like lines of growth when viewed under a lens. The descent of the body-whorl is very sudden and brief. The whorl, owing to the expansion of the peritreme, has a constricted appearance in that part. The umbilicus is a little more open than in H. congener, and consequently more perspective. The coloration of this species is not easily definable. The ground-colour is pale straw, the oblique raised lirae being more opaque and yellower. The body-whorl below the periphery is stained with brown, or looks as if it were scorched. The colouring takes the form of a very broad interrupted transverse band, or, in other words, of wide blotches or stripes. The latter are sometimes continued upon the upper half of the whorl, and are also here and there faintly observable on the upper volutions. One Helix (Camena) congenita. specimen has a narrow peripherial brown band. The body-whorl is stained with brown outside the tip; and this, owing to the thinness of the shell, produces a brownish labrum, which in some places, particularly at the extreme edge and in the columellar region, is somewhat whitish. It is rather widely expanded at the base and columella, and is a trifle reflexed everywhere. The aperture is very transverse, in fact almost horizontal; it is of a livid white colour within, exhibiting the brown marking of the exterior. Subgen. MYXOSTOMA, Troschel. Testa plus minusve discoidea, late umbilicata ; apertura circularis peristoma duplex, margine interiore superne plerumque leviter sinuato, externo supra sinum alatim expanso. Operculum corneum crassum, inferne paulo concavum, in medio nucleo prominulo, extus marginibus anfractuum lamellosis. This section of Cyclophorus agrees with Pterocyclos in the form of the shell and its peristome, but differs in having a thick horny operculum, with the margins of the whorls lamellated exteriorly, that of Pterocyclos being calcareous and spirally laminated. CYCLOPHORUS (MYXOSTOMA) BATHYRHAPHE. Testa discoidea, apertissime umbilicata, spira parum elevata epidermide luteo-olivacea sordide vel ceeruleo-albida; anfr. rotundati, sutura valde canaliculata srjuncti, ultimus sat maanu* |