168 TORNATELLINA. 



In the young stage, microstoma is very distinct by its la- 

 mellse and plicae. In a specimen 2.8 mm. long, 4% whorls 

 (pi. 33, fig. 8), the columella has a strong, subhorizontal cen- 

 tral lamella, a smaller, more delicate lamella above, and a 

 minute, very deeply immersed one below. In the palatal wall 

 there is a strong, serrate barrier, with another more deeply 

 placed, visible as a whitish streak outside. The parietal la- 

 mella flares outward in the middle. Younger examples, down 

 to 2 mm. long, have the same armature. 



The figures are from specimens from the Quadras collec- 

 tion. 



24. T. MOELLENDORFFIANA Pilsbry, ii. sp. PI. 38, figs. 7, 10, 11. 



The shell is imperforate, oblong-conic, brownish-corneous, 

 shining, very distinctly marked with growth-striae. The spire 

 has slightly convex outlines and an obtuse apex. Whorls 5^, 

 moderately convex, separated by a delicately margined 

 suture ; the last whorl flattened in the middle, its last half 

 rather deeply impressed there; base very convex, sack-like, 

 impressed around the axis. The aperture is quite oblique, 

 ovate. Columella short and vertical, heavily calloused, the 

 callus, in oblique view, is seen to emerge in an oblique, rounded 

 fold or plait, which projects forward in a short lobe, some- 

 what tooth-like, at its outer end. Some distance within the 

 basal lip there is a low callous ledge, given off from the colu- 

 mella ; it is more or less distinct within the outer lip also, as 

 far up as the median contraction, where there is usually a 

 more or less distinct callosity. The well-developed parietal 

 lamella enters deeply. Length 3.7, diam. 1.8, length of aper- 

 ture 1.2 mm. 



The immature stage (pi. 38, figs. 7, 10, 2.8 mm. long, with 

 nearly 5 whorls) has the aperture like the adult, except that 

 the callus within the outer .'and basal lips is stronger. 



Marianne Is.: Guam (Quadras), associated with T. micros- 

 toma. 



The adult stage of this species resembles that of T. micros- 

 toma Mlldff., but it is slightly more robust with more convex 

 whorls. The immature shells (figs. 7, 10) however differ 



