148 TORNATELLINA. 



below it a callus bearing a small tubercular tooth. This 

 structure resembles T. perplexa except that the lamella and 

 tooth are not quite so strong in T. societatis. Some distance 

 within the outer lip there is a very low, whitish, vertical, cal- 

 lus streak, occupying the position of the callus rib in Lami- 

 nella. Parietal lamella well-developed, entering about a half- 

 whorl, of about uniform height, its edge even. Length 3.25, 

 diam. 1.55 mm.; aperture 1.2 mm. 



Society Islands: Raiatea (C. D. Voy), type 110. 83155 A. N. 

 S. P. 



This form differs from T. nitida by its tridentate columella 

 and the very low callus in the palatal region, in place of den- 

 ticles. In T. perplexa the columellar lamella is prominent in 

 ,the adult stage in a front view, but in societatis it is im- 

 mersed. It must be admitted, however, that specific relations 

 in the perplexa group are only imperfectly understood. We 

 have not the large lots containing shells in all stages of growth 

 which are essential to an adequate understanding of the 

 group. Meantime, the form defined above seems to be distinct 

 from the allied species. It seems intermediate between the 

 perplexa group and Lamellina. 



11. T. COLUMELLARIS MoUSSOn. 



Shell imperforate, elongate-conic, pellucid, slightly striatu- 

 late, glossy, pale corneous. Spire regular conic, the summit 

 rather acute, minute; suture impressed, simple. Whorls 5, 

 rapidly increasing, convex, the last not descending, larger, a 

 little swollen above and below, not impressed in the middle. 

 Aperture slightly oblique (20 degrees with axis), scarcely 

 one-third the length, oval. Peristome unexpanded, acute ; 

 margins not approaching, the right margin arcuate, colu- 

 mellar margin adnate above. Columella bearing an acute, 

 subhorizontal, deeply placed fold, continued forward in the 

 somewhat thickened margin. Length 2.8, diam. 1.6 mm. 

 (Mouss.). 



Fiji Is.: Kanathia (Dr. Graeffe). 



Tornatellina columellaris Mouss., Journ. de Conchyl., 1870, 

 p. 129. PFR., Moiiogr., viii, 316. 



