362 PROCEEDINGS OF THE ACADEMY OF [May, 



the southern part of Yesso. So far as present information goes, no 

 species of the group occurs in Shikoku, southwestern Nippon or 

 Kyushu. It seems to be a group of middle and northern Nippon. 

 The most important structural peculiarities of the group are the ab- 

 sence of any pronounced emargination or excision of the clausilium 

 on the columellar side of the filament, and the lack of a lower pala- 

 tal plica. All the species are pale-colored. 



Most of the species defined by von Mollendorft have not been 

 figured, and were apparently described from very few specimens. 

 In studying them I have found the table opposite, compiled from 

 the original diagnoses, a useful aid ; 2 and its publication may assist 

 others. 

 Clausilia heteroptyx n. sp. PI. XVIII, figs. 17, 18, 19, 20, 21, 22. 



Shell rimate, stoutly fusiform, solid, light yellow, the cuticle 

 partly worn off, somewhat glossy, lightly striate, a little more 

 strongly so just behind the lip. Spire rather thick, regularly taper- 

 ing, not attenuated, the apex obtuse. Whorls 9, but slightly con- 

 vex, the last flattened, rounded beneath. Aperture but slightly 

 oblique, ovate, the peristome continuous, appressed to the preceding 

 whorl above, expanded and reflexed. Superior lamella oblique, 

 rather high, continuous with the spiral lamella, which penetrates 

 to about the middle of the ventral side. Inferior lamella forming 

 a distinct though obtuse fold on the columella, somewhat thickened 

 and bifurcate within, rather straightly ascending and thickened 

 within the dorsal side, penetrating further than the spiral lamella. 

 Subcolumellar lamella slightly immersed, the end visible in a front 

 or oblique view, but not extending upon the lip. Principal plica 

 not quite a half whorl long, the lower end visible deep in the throat, 

 extending inward past a lateral position. Lunella straight and 

 narrow, one or two short, oblique palatal plicse above it. 



Length 26.5, diam. 6.6, length of aperture 7.8 mm. 



Length 25.2, diam. 6.5, length of aperture 7.2 mm. 



Length 24, diam. 6. 5, length of aperture 7 mm. 



Clausilium not much curved, long, narrow and parallel-sided, the 

 palatal side somewhat thickened, apex rather acuminate; there is 

 no noticeable excision or emargination near the filament (PI. 

 XVIII, figs. 21, 22). 



2 The model is that of Prof, von Martens, used very successfully by 

 him in the land mollusks of the Biologia Centrali Americana. 



