134 AMASTRA. 



Shell usually dextral, varying from globose-conic to oblong- 

 conic; umbilicate or imperf orate ; dull or dark colored, or 

 light with a dull, darker or yellowish cuticle; whorls 5% to 

 8; spire and apex conic. Aperture ovate, the outer lip not 

 expanded, often thickened within ; columella bearing a spiral 

 lamella which penetrates about a half whorl, but is present 

 at all stages of growth examined ; above it the axis is slightly 

 sinuous. Viviparous, jaw vertically striate, teeth in nearly 

 straight transverse rows, of the usual quadrate form, the 

 centrals narrow with small cusp. 



Type: A. magna C. B. Ad. Distribution: Kauai, Oahu, 

 Lanai, Molokai, Maui and Hawaii; living on the ground 

 under leaves, etc., or rarely on ferns and low bushes, in the 

 mountain forests. 



Amastra, as constituted by H. & A. Adams, 1855, was a 

 homogeneous group, comprising the species baldwini Newc., 

 biplicata Newc., ellipsoidea Gld., gigantea Newc., magna C. 

 B. Ad., melampoides Pfr., moesta Newc., nucleola Gld., obesa 

 Newc., obscura Newc., reticulata Newc., tristis Fer., ventulus 

 Fer., violacea Newc. In Die Heliceen, 1860, von Martens 

 distributed the species in Laminella and Leptachatina, ignor- 

 ing Amastra. Pease, 1869, gave a classified list of species in 

 which several natural groups within the genus were recog- 

 nized. Gulick, in 1873, selected A. magna as the type of 

 Amastra. 



Amastra differs from the more primitive genus Leptachat- 

 ina by its more conic apex, that of Leptachatina being 

 rounded. The shell is generally duller, often with a par- 

 tially deciduous outer cuticle, wanting in Leptachatina, and 

 it differs more fundamentally by the viviparous reproduction. 

 Carelia is closely related to Amastra, young shells of some 

 species being quite Amastrif orm ; but the adult stage is more 

 lengthened and columnar, and the jaw is said to be ribbed. 

 The relationship between Amastra and Laminella is very in- 

 timate ; indeed the two groups are separated generically in 

 this work more as a matter of convenience than for any im- 

 portant structural character known to exist, though they 

 are no doubt natural groups. If consolidated into one genus, 



