166 TOKNATKLL1NA. 



'2~2. T. SUBCYLINDRICA Quadras et Moellendorff. PI. 33, figs. 

 10, 11. 



Shell not rimate, subcylindric-turrited, delicately striatu- 

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

 jrni dually tapering, the apex rather obtuse. Whorls 6y 2 , 

 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 plica. Length 3.33, diam. 

 1.5 mm. 



In the young the columella is bidentate and the last whorl 

 provided with internal ribs as in the preceding species 

 (Mlldff.). 



Marianne Is.: Guam (Quadras). 



Tornatellina (Lamellina) siibcylindrica Q. et MLLDFF., 

 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, 

 ;ind 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 lohe standing then directly towards the observer. 

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

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

 oblonga. 



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

 with 414 whorls) have convex whorls, the last marked with 

 one or two whitish streaks outside, marking the positions of 

 strong, whitish, verliciilly placed internal palatal laminae, ser- 

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



