166 TORNATELLINA. 



22. T. SUBCYLINDRICA Quadras et Moellendorff. PL 33, figs. 

 10, 11. 



Shell not rimate, subcylindric-turrited, delicately striatu- 

 late, thin, subpellueid, a little shining, buff-corneous. Spire 

 gradually tapering, the apex rather obtuse. Whorls 614, 

 rather convex, the last more distinctly plicate-striate, from 

 the beginning rather deeply impressed spirally in the middle. 

 Aperture moderately oblique, rounded-trapezoidal ; peristome 

 simple, acute. Columella dilated above, running forward 

 forming a dentiform process, strongly twisted spirally, sub- 

 dentate above. Parietal lamella oblique, strongly elevated, 

 extending deep within ; no palatal plicae. Length 3.33, diam. 

 1.5 mm. 



In the young the columella is bidentate and the last w r horl 

 provided with internal ribs as in the preceding species 

 (Jtttdff.). 



Marianne Is.: Guam (Quadras). 



Tornatellina (Lamellina) subcylindrica Q. et MLLDFP., 

 Nachrichtsblatt d. D. Malak. Ges., vol. 26, Feb., 1894, p. 16. 



In the immature stage this snail has serrate palatal bar- 

 riers, like T. serrata, but these are lost in the adult stage, 

 which has also a simply twisted columella. An abundant 

 series shows much variation in the contour of the last whorl, 

 which may be impressed in the middle, as described above, 

 and shown in fig. 10, or merely flattened there. The columella 

 is rather heavily calloused, moderately twisted, and projects 

 forward in a strong, dentiform lobe. This is prominent in a 

 profile view from the left side, though not shown in a front 

 view, the lobe standing then directly towards the observer. 

 An average adult shell measures, length 3.1, diam. 1.3, alt. of 

 aperture 1 mm. (fig. 10). In the adult stage it resembles T. 

 oblong a. 



The young (metaneanic) shells (pi. 33, fig. 11, 2 mm. long 

 with 4!/4 whorls) have convex whorls, the last marked with 

 one or two whitish streaks outside, marking the positions of 

 strong, whitish, vertically placed internal palatal laminge, ser- 

 rate at the edge. The columella is tridentate, like that of T. 



