172 AMASTRA, OAHU. 



was in error, for a thin cuticle exists, as in all the Metamastra?, 

 though there is no dull or dark outer layer. 



A. p. breviata, while connecting with A. pellucida through 

 various shells of intermediate shades of brown, is 'also, on the 

 other hand, quite as closely connected with A. textilis. Typi- 

 cally breviata is more obese than textilis, a little thinner, a 

 trifle more roughly wrinkled, less glossy, and it often has 

 hydrophanous bands; but I would not care to attempt the 

 separation of a mixed lot. 



In a series from Waimano in coll. C. M. Cooke the color is 

 rich red-brown, varying in intensity. One shell has an in- 

 terrupted buff line near the suture, and a small yellow area 

 at the axis, the others being one-colored. The shell is thinner 

 than in typical breviata (pi. 30, fig. 15). 



Probably A. breviata will be found to range from Palolo 

 to Waimano. In its characters and distribution it lies be- 

 tween textilis and pellucida, though of course separated from 

 the latter by the arid inter-montane belt. 



17. A. IRWINIANA Cooke. PL 30, fig. 16. 



"The shell is minutely (though distinctly) perforate, dex- 

 tral, globosely conical, with slightly concave outlines, thin, 

 distinctly irregular and closely striate with lines of growth, 

 not glossy, the upper whorls and the base of the last whorl 

 light brown with a slightly yellowish tinge, the upper por- 

 tion of the last whorl of a dark chestnut. Spire slightly con- 

 cavely conic, apex acute. Suture simple, well impressed. 

 Whorls 614, 'the embryonic slightly swollen, the fourth and 

 fifth slightly flatter, the last convex, tumid, with an almost 

 obsolete angle at the periphery, tapering towards the base. 

 Aperture rather large, bluish within, in the form of a slightly 

 oblique sector of a circle, very slightly oblique. Columella 

 straight ; columellar fold almost median, rather large, thin and 

 slightly oblique. Outer margin of the lip thin, slightly thick- 

 ened within, erect, regularly curved, forming an angle with 

 the base of the columella ; columellar margin thin, reflexed 

 above the umbilicus. Umbilicus minute, semicircular. Length 

 11.2, diam. 7.2, length of ap. (diagonal) 5.9 mm." (Cookf). 



