1904.] NATURAL SCIENCES OF PHILADELPHIA. 835 



view, though seen obliquely from the base it appears as a rather high 

 thin lamella. Within it ascends in a widely spiral curve. The sub- 

 columellar lamella emerges to the lip-edge, and ascends in a sigmoid 

 curve. The principal plica is about a half whorl long, dorsal and 

 lateral. The u])pcr palatal plica is veiy oblicj[ue, and weakly joined 

 to the lunella, which is oblique, straight above, arcuate, curving inward 

 below. 



Length 10.5, diam. 2.5 mm. 



Clausilium (PI. LVII, figs. 100, 101, 104) short and wide, well curved, 

 at the distal end tapering to a blunt apex, somewhat excavated on the 

 palatal side. It is deeply excised on the columellar side of the filament. 

 On the outer, convex surface there is a transverse plate extending from 

 side to side. 



Kumejima, Ryukyu. Types No. 87,631, A. N. S. P., from No. 1,293 

 of Mr. Hirase's collection. 



Externally this species is much like the striate species of Zaptyx, 

 but the sigmoid lamellse and unique clausilium distinguish it. 



Section OLIGOZAPT^^K nov. 



The shell is very small, fusiform, with no superior lamella. The 

 inferior lamella forms a squarish fold in the throat and the subcolu- 

 mellar lamella is obsolete below. There is a long lower palatal plica 

 and short upper united with the lunella. Sutural plicae and a lamella 

 fulcrans are developed. The clausilium is notched on the palatal side 

 of the projecting apex, and excised on the columellar side of the fila- 

 ment. 



Type C. hedleyi. 



In this extraordinary phylum the clausilium resembles that of 

 Diceratoptyx, while the palatal armature is totally unlike any other 

 known Zaptychoid form by the development of a large lower palatal 

 plica. The whole closing apparatus is of a highly evolved type. 



Clausilia hedleyi n. sp. PI. LVII, figs. 105-110. 



Shell very small, jusiform, attenuated above, amber-colored, trans- 

 parent; almost smooth, with a brilliant gloss, the last whorl slightly 

 striate behind the lip. Whorls 7|, convex, the last narrow and taper- 

 ing downward. Aperture projecting free in front, piriform, the white 

 lip narrowly reflexed. Superior lamella obsolete, represented merely 

 by a slight thickening of the peristome. Spiral lamella small, low and 

 short, lateral. Inferior lamella receding, forming a strongly projecting 

 squarish and bifid fold in the throat, low within. Subcolumellar 



