1908.] NATURAL SCIENCES OF PHILADELPHIA, 583 



Length 12.5 to 13.5, diam. 3.0 mm. 

 11, " 2.9 " 



The clausiHiim is quite broad, rounded at the apex, deeply excised 

 on the cokimellar side of the filament. Its curvature is chiefly in the 

 part near the filament. 



Nakanoshima, Osumi. Types No. 95679 A. N. S. P., from No. 1515 

 of Mr. Hirase's collection. Also Kuchinoshima. 



The type lot consists of very handsome, glossy, dark colored shells, 

 but there are some gray, corroded specimens among them, apparently 

 from a different situation. The smallest measures, length 11.5, diam. 

 3 mm., and has the penultimate whorl strongly swollen, the last whorl 

 compressed (fig. ll,c). 



This form is closely related to C. tokarana, but differs by its darker 

 color, swollen penultimate whorl, etc. It also resembles C. pattalus 

 of Tarama-jima and Miyako-shima, but it differs by having the penul- 

 timate whorl more swollen, the principal plica shorter, and the sub- 

 columellar lamella emerges. In both species the second whorl appears 

 disproportionately large. 



Examples from Kuchinoshima are corroded and dull, and have the 

 superior lamella separated rather broadly from the spiral lamella; 

 otherwise they do not differ from the types. 



The subspecies saccatihasis is confined to the two northern islands 

 of the Tokara group. 



Section IDIOZAPTYX n. sect. 



The shell is Zaptychoid externally. Superior lamella small, sepa- 

 rated from the much reduced spiral lamella. Inferior lamella receding, 

 massive, almost straightly ascending within. Upper palatal plica 

 long, the lunella descending from near its inner end, and joining the 

 inner end of the lower palatal plica; fulcrum and parallel lamella short 

 but distinct; sutural plicae developed. Clausilium excised and bent 

 near the filament, parallel-sided, rounded at the apex. Type C. 

 idioptyx. 



This section is related to Diceratoptyx^ but it differs in having a well- 

 developed lunella, joining the lower palatal pUca, in the straightly 

 ascending inferior lamella, and the very different clausilium, which 

 is hke that of Zaptyx. 



2 Proc. A. N. S. Phila., 1904, p. 836. To the diagnosis of Diceratoptyx should 

 be added . a small lower palatal plka is developed ; the inferior lamella ascends 

 in a broad, sigmoid curve. 



