AMASTRA. 37 



This is a member of the mucronata group, distinguished by 

 the very thin shell and the thin, wholly plain, russet cuticle, 

 which darkens to chestnut on the last whorl. It is a thinner 

 shell than A. subobscura. 



A. KALAMAULENSIS Pilsbry & Cooke, n. sp. PL 3, figs. 4, 5, 6, 7. 



The shell is imperforate or nearly so, ovate-conic, very thin, 

 glossy light brownish olive in front of the aperture, elsewhere 

 covered with a thin russet cuticle having darker or blackish 

 streaks on the last whorl, often wholly black in its last half, 

 and usually having a cream-white band at the periphery run- 

 ning a short distance in front of the aperture. The embryonic 

 whorls are flat, carinate and costate, the ribs coarser than in 

 Mapulehu A. mucronata. Subsequent whorls somewhat 

 convex, marked with irregular growth-lines. The acutely an- 

 gular periphery persists upon the penultimate whorl, but it 

 becomes rounded before reaching the last, where the position 

 of the keel is marked by a light band on the ventral side in 

 most individuals. The aperture is dark within, with no white 

 lining. Columellar fold thin. Columellar margin reflected, 

 nearly or entirely closing the perforation. 



Length 11.9, diam. 7, aperture 6.2 mm. ; 5% whorls. 



Molokai: Kalamaula. D. Thaanum. Cotypes no. 108227 

 A. N. S. P. and Bishop Museum. Also in Thaanum coll. 



This shell has the very thin texture of A. kaunakakaiensis, 

 from which it differs by the more prolonged carinate stage, 

 the more obese shape and the frequent presence of a whitish 

 band in front of the aperture. It has a thinner prismatic 

 layer than any form of A. mucronata or A. siibobscura, and 

 there is not the least trace of mottling or zigzag figures in 

 the cuticle. 



In a few specimens the embryonic whorls are slightly con- 

 vex, the riblets almost obsolete, and the peripheral keel con- 

 cealed. I cannot see that the rest of the shell differs. Similar 

 cases of heteromorphic embryos have been noted in a few 

 other Molokaian Amastras. By an error of the artist, figure 

 4 was grouped with figs. 1-3. 



