PRONESOPUPA. 17 



tended apical whorls and the absence of membranous edges 

 to the riblets. 



11. PRONESOPUPA SERICATA n. sp. PI. 1, fig. 1. 



The shell is perforate (umbilicus minute, circular, deep), 

 nearly cylindric, dresdeii brown, thin, slightly translucent, 

 the surface silky, closely and evenly costulate. Spire ex- 

 tended, with slightly convex outlines, the whorls convex, sep- 

 arated by a rather deep suture. Apex relatively acute. 

 Whorls 5y 2 , increasing very slowly and regularly, the embry- 

 onic, under the microscope, minutely granulose, then, begin- 

 ning gradually, the rest of the whorls are closely and evenly 

 costulate ; the riblets low, without membranous edges, on the 

 last whorl about 0.05 mm. apart, and, under a very strong 

 lens, crossed by minute, close, indistinct, raised spiral lines, 

 and with minutely granulose interstices. Last whorl slightly 

 broader than the penult, long, tapering towards the base, 

 convex around the umbilicus, slightly ascending near the 

 aperture. Aperture unarmed, hardly oblique, not diagonal, 

 nearly vertical, narrowly truncate-ovate, the lip-insertions 

 remote. Outer margin of the peristome indistinctly thick- 

 ened, not expanded, columellar margin triangular, arched 

 above the umbilicus, its inner face straight. Length 2.7, 

 diam. 1.41, aperture (diag.) 1.04 mm. Holotype 11035 Bishop 

 Museum; paratypes 39256 Bishop Museum and A. N. S. P. 



Hawaii: Piihonua, (a hill) in the flow of 1855, about 5,000 

 feet elevation, on leaves (type loc.) ; Humuula and Kipuu, in 

 1880 flow, above 6,000 feet (Forbes). 



A very rare and interesting species from the highlands of 

 Hawaii. All the specimens were taken by Mr. Forbes and 

 were found on the leaves of plants. The type material con- 

 sists of two adult (one of which is badly broken) and four 

 immature specimens. There are but two specimens from each 

 of the other two localities. 



This species is most closely related to P. f. corticicola from 

 Maui. It differs, however, in its more extended spire, less 

 convex outlines and especially in its coarser and more 

 strongly costate surface. 



