640 PROCEEDINGS OF THE ACADEMY OF [Dec., 



penetrates to or past the middle of the ventral side. Inferior 

 lamella approaching the superior, forming a strong, subhorizontal 

 fold; inside it ascends with a broad spiral trend, and penetrates 

 nearly or quite as far as the superior lamella. The subcolumellar 

 lamella emerges to the lip-edge. The principal plica is visible 

 deep in the throat and ascends to a latero-ventral position. Pala- 

 tal plicse three or four, the first and fourth long, oblique ; the 

 second shorter; third very small or wanting, leaving a space. 



Length 14 to 17, diam. 4 mm. (Von Martens* type). 



Length 17.2, diam. 4.3 mm.; length 14, diam. 4 mm.; length 

 13.4, diam. 3.5 mm. ; specimens from Tokyo. 



Length 14.5, diam. 4.1 mm.; length 12, diam. 3.5 mm.; 

 specimens from Nikko. 



Length 17, diam. 3.7 to 4 mm.; specimen from Numazu, 

 Suruga. 



Clausilium (PI. XXXVIII, figs. 52, 53) short and wide, broadest 

 below, strongly arcuate, a little tapering and thickened at the 

 apex, somewhat excised on the columellar side of the filament. 



Misaki, Sagami, at the mouth of the Bay of Tokyo (Hilgen- 

 dorf, type locality); Ashima, Izu (Hirase); Yokohama (B. 

 Schmacker); Tokyo (F. Stearns); Nikko, Shimotsuke (Loomis); 

 Fujisawa (Hungerford, type locality of C. tetraptyx~) ; Numazu, 

 Suruga (Hirase). 



The small size for a Stereophcedusa, strongly attenuated early 

 whorls, and thin shell are the more prominent differences between 

 C. brevior and other species of the group. * 



The area of distribution so far indicated is a rather restricted 

 district in middle Nippon. Mr. Hirase' s fruitful researches in the 

 southwestern half of Nippon and in Shikoku have not revealed the 

 species there; nor has it yet appeared from as far north as the 

 Province Uzen, whence a considerable number of small species 

 have been sent. It seems to be a very abundant shell in the region 

 about Tokyo Bay. 



The variety tetraptyx Mlldff. is a little darker brown, the peri- 

 stome brown-tinted, at least in part, the palatal plicse slightly 

 longer than in typical brevior ; but in the lot of some hundreds of 

 specimens I have seen, these characters, except as to the tint of the 

 lip, vary by insensible degrees, so that I do not see that tetraptyx 

 has a valid claim to varietal distinction. One of the original 



