266 ACHATINELLA C^ESIA. 



sinistral. The periphery is marked by a white band, with a 

 wide black band below, a narrow one above it. There is a 

 white band below the suture, bordered by an inconspicuous 

 yellowish line. The rest of the upper surface of the last whorl 

 has a light plumbago-gray hue, produced by darker and paler 

 streaks. The base has a blackish band around the columella, 

 and is elsewhere white. The embryonic whorls are white; 

 following whorls of spire have a dark band above and below 

 the suture, which runs in a white band. Columellar fold 

 white and very strong; aperture white within, the acute, 

 beveled lip is colored at the terminations of bands ; somewhat 

 thickened. Length 19.5, diam. 10.5, aperture 9 mm. ; 6*4 

 whorls. 



A. formosa is merely concidens with black bands added. 

 It seems remarkable that Mr. Gulick did not recognize in 

 casia, concidens and formosa merely three stages in the de- 

 velopment of pattern, strictly comparable to several other 

 well-known species which have the same sequence of patterns 

 streaked, streaked and with white spiral bands, and the 

 same with dark bands. 



Kahuku: in troughs of sand dunes near the sea, between 

 the road and the shore, about 1^ miles east of Kahuku, pi. 

 44, figs. 17 to 20, collected by Cooke and Pilsbry. This fossil 

 form is a fairly well-marked subspecies which may be called 

 A. c&sia littoralis P. et C. It differs from c&sia and its 

 Waimea color-forms by the rougher surface, which is decidedly 

 more wrinkled along lines of growth, especially on the last 

 half of the last whorl, and the columellar fold is unusually 

 high on the columella, less prominent than in adult Waimea 

 shells. The shell is thin, minutely perforate, varying in shape 

 as figured, and marked with several broad or numerous narrow 

 dark zones (gray, or in places brick-red in the fossils, prob- 

 ably almost black when they were alive) ; all had a white 

 subperipheral band. 



Length 20, diam. 10.6, aperture 9 mm.; whorls 6y 2 . 



Length 20, diam. 11, aperture 10 mm. ; whorls 6^. 



Length 19.8, diam. 11.6, aperture 10.3 mm. ; whorls 5%. 



The deposit at Kahuku contains many Tornatellinidce and 



