642 PROCEEDINGS OF THE ACADEMY OF [Dec. , 



swollen, latter half of the last whorl compressed. Surface glossy, 

 sculptured with strong, threadlike oblique striae, 3 or 4 earlier 

 whorls smooth, usually Worn or eroded. Whorls 9 to 9^-, quite 

 convex, and separated by deeply impressed sutures. Aperture 

 slightly oblique, ovate-pirifonn, the peristome very shortly free 

 above, expanded and reflexed, whitish, slightly emarginate at the 

 position of the superior lamella, the sinulus a little retracted. 

 Superior lamella slender, vertical, continuous with the spiral 

 lamella, which extends inward to the middle of the ventral side. 

 Inferior lamella forming a rather small but subhorizontal fold, not 

 reaching out upon the lip, extending inward as far as the superior 

 lamella. Subcolumellar lamella varying from barely immersed to 

 rather weakly emerging. Principal plica a half-whorl long, ex- 

 tending from a dorsal position (visible deep in the throat) to a 

 latero-ventral position. Upper and lower palatal plicae rather 

 short, lateral. Below the upper palatal plica there is a delicate 

 second plica, from the outer end of which a low straight lunella 

 runs to the lower palatal plica. 



Length 15.5, diam. 3.6 mm. ; length 13.6, diam. 3.5 mm. 



The clausilium (PI. XXXIII, figs. 61, 62) has the general 

 shape and curvature of that of C. brevior and Addisoni, but differs 

 from both in having the apex more pointed, and it is more concave 

 on the palatal side of the apex. The end is also more thickened 

 than in C. brevior. 



Tane-ga-shima, Osumi. Types No. 82,277 Coll. A. N. S. P., 

 from No. 754 of Mr. Hirase's collection. Also Yaku-shima, No. 

 778 of Mr. Hirase's collection. 



This species is related to C. Stearnsii Pils. of Okinawa and C: 

 Addisoni Pils. of southern Kiushiu. It is much more slender than 

 the latter, with more convex whorls and a more pointed clausilium. 

 C. Stearnsii is a longer species, in which the early whorls are not so 

 attenuated. These three species have a low and more or less well- 

 developed lunella when adult, a structure occurring also in some 

 specimens of C. hondana, but otherwise unknown in the Stereoplice- 

 dusce of Nippon. In immature shells a row of short palatal plicae 

 stands in place of the lunella (fig. 68). 



This Clausilia has the thin shell of the other species of the 

 brevior group, while all other Clausilice known from Tane-ga- 

 shima are extremely thick and strong. 



