AMASTRA, OAHU. 205 



The embryonic shell has some faint growth-lines only, 

 thereby differing from A. rub ens. The young are acutely 

 angular up to nearly 10 mm. long, as in decorticata, etc. The 

 outlines of the spire are usually convex, and the summit is 

 obtuse. The columella and basal curve of the peristome are 

 frequently roseate. Waialei shells measure : 



Length 15, diam. 8.5, aperture 7.3 mm. ; whorls 5. 



Length 13.4, diam. 8.9, aperture 7.2 mm. ; whorls 5. 



Length 15, diam. 9, aperture 7.3 mm. 



Shells from Kawailoa have a 'blackish, more deciduous outer 

 cuticle, and the shell beneath is pinkish or bicolored. The 

 shells from Hanula and those from Kahuku are often paler 

 than usual in the type locality. Three from Kahuku figured 

 measure : 



Length 16.3, diam. 9, aperture 7.4 mm. ; whorls 5%. 



Length 14.6, diam. 9, aperture 8.2 mm. ; whorls 5. 



Length 15, diam. 8, aperture 7.5 mm. ; whorls 5%. 



An average shell and two extremes of shape from Kahuku 

 are figured, pi. 34, figs. 17 to 19. 



Mr. Sykes remarks that two specimens collected by Mr. 

 Perkins on Waianae Mts. may belong to a large, incrassate 

 variety. I think that they will prove specifically different. 



43. A. TRISTIS (Ferussac). PI. 32, figs. 1 to 7, 10, 13. 



The shell is imperforate or rimate, oblong-conic, rather 

 solid, ground-color of first 2 or 3 whorls blackish-purple, 

 fading then to red-brown with a pale sutural margin, and 

 finally diluted to light red-brown or nearly white on the last 

 whorl; the last 2 or 3 whorls having a thin dark brown or 

 blackish cuticle which is deciduous, remaining in angular 

 shreds and patches, generally lost over an area in front of the 

 aperture. Spire a little convexly conic, acute. Whorls 5% 

 to 5%, nearly flat, the first nearly smooth, the next having 

 regular radial ripples, following whorl with fine growth-striae 

 only. The last two whorls are marked with rather coarse 

 wrinkles along the lines of growth, and some fine spiral striae ; 

 and on the last whorl there are usually several unevenly- 

 spaced spiral grooves. The aperture is ovate, slightly ob- 



