PRONESOPUPA. 7 



on the last whorl. They are thin, membranous, of a uniform 

 height, the upper part not being produced into a spine. The 

 interstices between the riblets of the last whorl are covered 

 with very minute, close, discontinuous wrinkles. In an em- 

 bryonic specimen from Hawaii, the mother of which is iden- 

 tical with Ancey's types, the surface is minutely, though dis- 

 tinctly, closely punctate, the points being arranged in axial 

 rows ; with the growth of the shell these points gradually 

 unite, forming low close riblets. 



4. PRONESOPUPA HYSTRICELLA n. sp. PL 1, fig. 12. 



The shell is perforate (umbilicus small, circular, open, 

 deep, largely covered by the dilated columellar lip), helicoid, 

 clay color, thin, subtranslucent, conspicuously costate; the 

 riblets delicate, thin, transparent, membranous, forming on 

 the last and penult whorls, just above the periphery, delicate, 

 flat spines. Spire depressed, with slightly convex outlines 

 and obtuse apex, the w r horls very convex and separated by a 

 deep suture. Whorls 4, the embryonic I 1 /*? whorls finely 

 and closely granulose, the granules more or less arranged in 

 transverse rows, gradually forming riblets towards the end of 

 the second whorl, the last two whorls being strongly costate ; 

 the last whorl very large, depressed, convex around the um- 

 bilicus, slightly descending near the aperture, furnished with 

 28-30 costee, about 0.2 mm. apart, the intercostal surface 

 being more or less evenly minutely wrinkled. Aperture large, 

 oblique, truncate-ovate, slightly flattened on the right side, 

 forming a blunt angle at the shoulder, toothless. The outer 

 edge of the peristome is slightly expanded, thin; the eolu- 

 rnellar margin broadly dilated above the columella. 



Length 1.65, diam. 1.6, aperture, greatest length 0.92 mm. 



Length 1.5, diam. 1.7 mm. 



Hawaii: Hilo, Reed's Island (type loc.) ; Holotype 11032 

 Bishop Museum, Paratypes 23233 Bishop Museum and A. N. 



5. P. 



Kauai, a single specimen; Oahu, common; Molokai, not 

 rare ; Lanai, a single young specimen, doubtfully reported to 

 this species; W. Maui, not rare; E. Maui, rather common; 

 Hawaii, common. 



