TORNATELLINA. 135 



a. Shell oblong-conic or ovate-conic; whorls less than 7. 



b. Aperture having a parietal and a columellar lamella 

 and two palatal plicae or two spiral series of teeth, at 

 least in the neanic stage. Section Tornatettina, species 

 no. 1 to no. 12. 



b 1 . Aperture having a parietal and one to three columellar 

 lamellae, and successive vertical palatal ribs in the 

 neanic stage, sometimes persisting in the adult stage. 

 Section Lamellina, species nos. 13 to 24. 

 b 2 . Columella sinuous, parietal wall lamellate; no palatal 

 teeth or ribs at any stage of growth. Section Torna- 

 tellinops, species nos. 25 to 47. 



(/'. Shell long- tur rite or conic; whorls 9 or 10, flattened. Sec- 

 tion Elasmatina, species nos. 48 to 51. 



Adult individuals of the first two sections are phylogerontic 

 in some species, becoming secondarily simplified in the adult 

 stage, and indistinguishable from species of Tornatellinops. 

 Tlie classification of species known by the adult stage only is 

 therefore uncertain in some cases. 



Geographic Distribution and Keys to Species. 

 Species of Japan, the Loochoo and Bonin Islands. 



a. Shell having a vertical rib or ribs within the outer lip; 



length 3 to 3.2 mm., with 5 to 51/2 whorls. 

 b. Adult with strong lip-rib and no palatal ribs ; columella 

 thick, minutely biplicate; neanic stage with 2 or 3 

 columellar lamellae and serrate palatal ribs. Ogasa- 

 wara (Boiiin) Is. T. ogasawarana, no. 13. 



b 1 . Adult with thin lip and a smooth palatal rib. 



T. biplicata, no. 14. 

 a>. No palatal or lip ribs. 



b. Shell rather obese, the diani. more than half of length. 

 c. Length about 3.3 mm. ; 41/^-5 whorls. 



d. Parietal lamella low but long ; Loochoo Is. 



T. rucuana, no. 26. 

 d 1 . Parietal lamella wanting; Bonin Is. 



T. monodonta, no. 25. 



