254 AMASTRA, MOLOKAI. 



Newcomb has related in great detail his adventures in col- 

 lecting this snail, but did not mention the location of the pali 

 where he found it information more useful if less thrilling. 

 We do not know exactly what form Mr. Baldwin reports 

 from Mapalehu, which is on the southeastern slope. 



Newcomb declared A. umbilicata Pfr. to be connected with 

 petricola by intergrading specimens, a view accepted by 

 Pfeiffer in the Monographia, and also by Sykes and Borcher- 

 ding. Hartman kept them separate, I believe correctly. The 

 two species were mixed in material sent out by Newcomb, 

 and both were included in his several descriptions, though 

 the umbilicata form only incidentally, in the two phrases 

 " sometimes the last one inflated " and " often with an um- 

 bilicus." The form figured by Boreherding is evidently 

 neither petricola nor umbilicata. 



A. petricola is ovate-conic with the outlines of the spire 

 barely convex, nearly straight. The embryonic shell has ex- 

 tremely fine longitudinal striae, the later whorls rather coarse, 

 low, growth-folds. The shell is of a slightly olive-tinted brown 

 color, the embryonic whorls the same or purple-black. After 

 the embryonic stage there is a yellow line below the suture, 

 becoming a well-defined band on the last 1% or 2 whorls. 

 Back of the lip there is a rather broad yellow streak, which 

 extends to the umbilical region where it forms a yellow cres- 

 centric patch around the narrowly umbilicate axis. There is 

 a sort of obtuse ridge around the umbilicus. The outer 

 cuticle, visible in fresh specimens, under a lens, is an exces- 

 sively thin, dull, light-brown film over the glossy under layer, 

 which shows in angular patches. Outer lip acute, margined 

 with a white callus within. Columella vertical, its edge re- 

 flexed in a narrow triangle, overhanging the umbilicus, and 

 slightly channeled at the junction with the basal lip. It bears 

 a rather strong fold, which terminates rather far from the 

 margin. 



Length 10.2, diam. 5.9, aperture 3.9 mm. ; 5% whorls. 



Length 9.2, diam. 5 mm. ; 5% whorls. 



The specimens described and figured are from Newcomb, 

 and presumably part of the original lot. 



