162 AMASTRA, OAHU. 



differs from the others by its rough sculpture and large size. 

 The thickening-up of the parietal callus is probably an old- 

 age feature, which is often correlated with increasing aridity 

 of station. Figured from a co-type in coll. A. N. S. P. 



Section METAMASTRA Hyatt & Pilsbry. 

 Imperforate or narrowly rimate Amastrae with very finely 

 striate or smoothish embryonic whorls, strong, subhorizontal 

 columellar lamella, the sinus below it narrow and deep, some- 

 what spout-like. Type A. variegata Nc. 



Series of A. variegata. 



Amastrae of compact shape, the spire usually convexly 

 conic, whorls 5% to 6%; apex rather obtuse, the embryonic 

 whorls convex, very finely striate or nearly smooth (except in 

 A. badia) ; later whorls with no dull outer coat of cuticle, 

 usually variegated with opaque buff interrupted bands or 

 streaks ; rather glossy. Outer lip generally thickened within ; 

 columellar lamella strong, subhorizontal, the sinus below it 

 rather spout-like. 



These forms differ from the group of A. rub ens and in flat a 

 chiefly by the spout-like basal sinus of the aperture, produced 

 by an angulation of the whorl around the axis, noticeable be- 

 hind the columella in adult shells, while in the neanic stage 

 the basal part of the shell is rather straightly conic. The 

 cuticle, moreover, never has a conspicuous, dull, deciduous 

 layer, as is usual in the in flat a group. 



This Oahuan group has been differentiated from Amastrella 

 by the development of variegated coloration in the ''middle 

 layer" (not the outer, more or less deciduous cuticle, -as in 

 variegated species of Molokai and Maui), and by the peculiar 

 shape of the sinus below the columellar lamella, It com- 

 prises two series of species: Series of A. variegata (see below), 

 and Series of A. cornea, 'acutely ovate shells with the spire 

 attenuate, species 41 to 44. 



Metamastra is here used in a somewhat wider sense than 

 originally limited by the senior author. 



The reticulata series is copiously developed in the eastern 



