14 PRONESOPUPA. 



4, increasing very slowly and regularly, the embryonic 

 whorls nearly smooth, under a very strong lens very minutely 

 granulose, then, beginning gradually, the rest of the whorls 

 are closely and evenly costulate, the costas without mem- 

 branous margins, 011 the last whorl less than 0.04 mm. apart, 

 the interstices not wrinkled, but under the microscope there 

 are very indistinct, close, short spiral lines perpendicular to 

 the riblets. The last whorl is not very large, tapering towards 

 the base, convex about the umbilicus, ascending slightly near 

 the aperture. Aperture rather small, not diagonal, hardly 

 oblique, toothless, truncate-ovate, lip-insertions remote. Outer 

 margin of the peristome minutely thickened, slightly ex- 

 panded, coluniellar margin arched over the umbilicus. 



Length 2.05, diam. 1.15, aperture 0.73 mm. 



Length 2.1, diam. 1.15, aperture 0.7 mm. 



E. Maui: Ainahou, at the head of the Keanae Gap, Halea- 

 kala (type loc.) and Halemau, near the head of the Kaupo 

 Gap (Cooke), Ukulele at 6,000 ft. (Forbes, Cooke). On the 

 fronds of living ferns. Holotype 11033 Bishop Museum; 

 paratypes 38486 Bishop Museum and A. N. S. P. 



A rather rare species in collections, probably due to the 

 station and the difficulty of finding specimens. All the speci- 

 mens were found on the pinnies of large ferns (Sadleria) , 

 close to the mid-rib. 



Fully adult specimens, from Ukulele, have a minute colu- 

 mellar fold, which is slightly oblique, median in position and 

 situated deep within. These specimens are slightly smaller, 

 and with slightly more convex outlines than those from the 

 type locality. One measures : length 1.95, diam. 1.1 mm. 



There is no indication of a coluniellar fold in any of the 

 specimens from within the crater of Haleakala. 



8. P. frondicola corticicola n. subsp. PI. 1, fig. 3. 



This form is somewhat similar to the typical one. In the 

 subspecies the indistinct spiral lines are slightly more evident 

 under a strong lens and the shell is considerably larger and 

 stouter, with the same number of whorls. The figures are 

 drawn to the same scale. The last whorl ascends slightly 



