ACHATINELLA CESTUS. 287 



simulans, wherein no related form occurs. Both by the char- 

 acters of the shell and by geographic range, cestus seems to 

 be somewhat isolated. 



Towards the eastern end of the range the shell becomes 

 darker, with various modifications of pattern. It is these 

 most remote eastern forms which look like shells of the western 

 mountains. See under A. siviftii of the polymorpha pattern. 



Palolo. A. cestus was given a wide range of color and pat- 

 tern in Dr. Newcomb's description, and his figure, reproduced 

 in pi. 29, fig. 8, represents one of the very rare patterns, by 

 no means a fair representative of the species. This pattern 

 was indeed included by him as exceptional, ' ' sometimes with 

 blotches' etc. The normal or predominant coloration of 

 Dr. Newcomb's collection is shown in pi. 52, figs. 12, 12a, 

 representing two specimens received from him. 



The ground-color is cinnamon or a tint of that, obliquely 

 marked with streaks (often crenulate or broken into mottling) 

 of chestnut or chocolate, interrupted by a white band or line 

 below the periphery, another often wider, at the base, and fre- 

 quently a band below the suture. Embryonic whorls are 

 typically white with a small terminal comma or vortex of deep 

 livid brown or dark purplish gray; but often the embryo is 

 more or less stained with some tint of ocher or olivaceous. 

 The moderate lip-callus is tinted with flesh-pink. Length 

 15.5, diam. 11 mm. Length 17, diam. 10.5 mm. 



Mr. Gulick collected similar specimens in Palolo. Three 

 unusual color-forms are figured, pi. 52, figs. 14, 14a, and pi. 

 55, fig. 1. A large majority of the shells are sinistral. Mr. 

 Wilder got a few cestus on the Palolo-Manoa ridge, which 

 seems to be its extreme range in this direction. 



A mutation of cestus very distinct in appearance was taken 

 by Newcomb and Gulick in Palolo, pi. 55, figs. 2, 3, 4, coll. by 

 Gulick. The chestnut coloring is reduced to lines and bands 

 at the periphery and on the base. The shell resembles A. simu- 

 lans, but is less robust, the spire more slender, and the colu- 

 mellar margin less developed. Most of those collected by New- 

 comb and Gulick are sinistral. A small lot, no. 42 coll. Irwin 

 Spalding, consists of dextral shells, which occurred with the 



