252 AMASTRA, MOLOKAI. 



liptical, angular at both ends; columellar fold compressed, 

 deep, subtransverse. Peristome simple, acute, the columellar 

 margin somewhat dilated, and free throughout. Length 10%, 

 diam. 5% mm. (Pfr.) 



Oahu (D. Friek in Cuming coll. ; see below) ; Molokai (New- 

 comb) ; Mapulehu (Baldwin). 



Achatinella umbilicata PFR., P. Z. S., London, 1855, (Feb., 

 1856), p. 205, no. 15, no locality. Malak. Blatter, 1856, p. 

 165; Monographia, iv, 557 (Oahu, Frick). A. (Amastra) 

 umbilicata Pfr., HARTMAN, Proc. A. N. S., Phila., 1888, p. 

 50, pi. 1, f. 11. BALDWIN, Catalogue, 1893, p. 10. Achati- 

 nella petricola var., NEWC., Amer. Jour, of Conch., ii, p. 211, 

 pi. 13, f. 6. 



This species was described by Dr. Pfeiffer from a specimen 

 sent to Cuming by Frick, at first without locality, but later 

 with the locality Oahu. Dr. Newcomb in his Synopsis of the 

 genus Achatinella, 1858, p. 334, placed it as a synonym of his 

 A. petricola, from Molokai, -a position he upheld later in the 

 American Journal of Conchology, II. As Newcomb 's shells 

 agree fully with Pfeiffer 's description, we accept his iden- 

 tification, and figure a specimen received from him, discredit- 

 ing the locality Oahu, assigned on the authority of Frick. 



Differs from A. petricola by its larger umbilicus, thinner, 

 unicolored shell, the more slender spire, and the smaller, more 

 oblique columellar fold. In the specimens seen there is no 

 thickening within the outer lip. The two species are not very 

 closely related. 



The color is a rather light-brown, darker at the apex. The 

 embryo is possibly striate when quite fresh and unworn, but 

 is smooth in the specimens examined. Whorls more convex 

 than in A. petricola. The umbilicus is circular in a basal 

 view, and penetrates deeply, but is rather broadly overhung 

 by the columellar lip; an obtuse ridge bounds it, being em- 

 phasized by a spiral excavation just within its edge. The 

 aperture is angular at the junction of the columellar and 

 basal margins. The columellar margin is triangularly di- 

 lated, and bears a small, quite oblique fold, which emerges 

 more than that of A. petricola, nearly to the edge. There 



