524 PROCEEDINGS OF THE ACADEMY OF [August, 



II. Superior lamella wanting, or represented by a slight thicken- 

 ing of the peristome only. No lunella ; 2 palatal plicae. 

 a. Aperture piriform, . . Group of C. hung erf ordiana. 

 b. Aperture oval, hardly narrower above than below, 



Group of C. euholostoma. 



The groups are successively more aberrant in the order given 

 above, this phylum having its acme in the section Reinia. 



Two species, C. subgibbera and C. expansilabris, described by 

 Boettger from Kein's collection, are not known to me by specimens, 

 and their exact localities in Japan are unknown. All of Ihe other 

 species are represented in the collection of the Academy, and are 

 described and figured in this paper and preceding ones of the series. 



Group of C- shanghaiensis. 

 Key to Species. 



I. Superior lamella high; inferior lamella forming a conspicuous 



convex fold in a front view of the aperture ; subcolumellar 



lamella emerging; short upper and lower palatal plicae, 



but no trace of a lunella. Shell glossy, dark purplish - 



brown. 11.5 by 3 mm. Hachi jo Island, Izu, . C. tryoni. 



II. Superior lamella moderately developed; inferior lamella 



forming a low, convex fold in a front view, approaching 



close to the superior ; shell rib-striate. 



a. Brown; length 13-14 mm., .... C. digonoptyx. 

 a'. Greenish -corneous; palatal plicse short, lunella incon- 

 spicuous, almost wanting; length 10 mm., C. comes. 

 III. Superior lamella small or reduced to a low cord; inferior 

 lamella showing in front as a low fold, not converging 

 strongly toward the superior lamella; shell dull brown- 

 ish, finely striate. 



a. Superior lamella small but distinct; spiral lamella high; 



upper palatal plica long, connected in the middle with 



a J-shaped lunella, which is weak in the middle, and 



strengthened below into a nodule, .... C. tau. 



a'. Superior and spiral lamellae reduced to alow cord; palatal 



plicse short. 



b. Length 13-16, diam. 3-3.5 mm.; upper and lower 

 palatal plicse weakly connected by a low, imper- 

 fect lunella, visible as a whitish streak exter- 

 nally. Kyushu, C. subaculus. 



b'. Length 13.5, diam. 2.7 mm. ; small upper and lower 

 palatal plicse, but no lunella. Yesso, C. rowlandi. 



