274 ACHATINELLA. 



columellar dark patch. Embryonic whorls white, becoming 

 blue-gray at the tip. The surface is glossy, marked with fine 

 growth-lines and nearly obsolete spiral striae. Spire conic 

 with nearly straight outlines and minute apex. Suture very 

 narrowly margined in some, not in other specimens. The 

 aperture has a white lining, showing the bands faintly, but 

 at the thin edge they become vivid, the acute peristome being 

 elsewhere white. It is slightly thickened within. Columellar 

 fold strong and white. 



Length 19.1, diam. 11.6, aperture 10.3 mm. ; fully 6 whorls. 



Length 17.6, diam. 11, aperture 9.25 mm. 



Oahu, Waianae range: a gulch of Mt. Kaala running into 

 Haleauau gulch, on banana. D. Thaanum. 



This fine species is closely related to A. lehuiensis, but differs 

 by being more capacious with larger last whorl and aperture, 

 and somewhat different coloration, lacking subsutural and 

 columellar bands. It may eventually prove to be a subspecies 

 of lehuiensis if colonies intermediate in characters are found, 

 but with present knowledge a union of the two is not war- 

 ranted. A. thaanumi is a thicker, smoother shell than 

 A. spaldingi, with narrower aperture and somewhat different 

 coloration. It is one of the rarest Oahuan shells, only in the 

 collection of Mr. Thaanum, two specimens, one a dead but 

 fresh shell. 



Section ACHATINELLA s. str. 



Achatinella SWAINSON, Quarterly Journal of Sci. and Arts 

 iii, p. 83, 1828. Apex von Martens, Die Heliceen, 1860, p. 248, 

 "type Achatinella lugubris Chemn." Helicter (Fer.) PEASE, 

 Proc. Zool. Soc. London 1862, p. 3 ; 1869, p. 645. Helicterella 

 GULICK, Journal of the Linnean Society of London, Zoology, 

 xi, p. 497, 1873 (name only; no species mentioned). 



Shell ovate-conic or piriform, imperforate or minutely per- 

 forate, solid. Embryonic whorls nearly flat, the later ones 

 more convex. Aperture quite oblique, the lip very little if at 

 all expanded, well thickened within ; columellar fold strongly 

 developed. Type A. apexfulva. 



Distribution, both ranges of Oahu. 



