AMASTRA, KAUAI. 151 



The less swollen contour, open umbilicus and biangular 

 aperture distinguish this species from A. rugulosa, from which 

 it seems to be quite distinct. Five specimens examined, three, 

 including the one figured (figs. 13, 14), received from Pease. 



This form must be closely related to A. extincta, said to be 

 from Oahu, on the authority of Frick; but as described by 

 Pfeiffer, that shell is more slender, the aperture scarcely more 

 than one-third the length of the shell, while the aperture of 

 similaris is about half as long as the shell. Compared with 

 A. morticina of Maui, A. similaris differs by its less attenuate 

 early whorls. 



Other specimens received from the Pease collection in Mus. 

 Cornp. Zool. are labeled Waimea, a place on the southwest 

 coast of Kauai. They are somewhat more slender than those 

 described above but agree with them otherwise. 



Length 12.2, diam. 6.8, aperture 5.9 mm. (fig. 7). 



Length 11.5, diam. 7 mm. 



Subgenus AMASTRA H. & A. Adams. 

 Section AMASTRELLA Sykes. 



Amastrella SYKES, Fauna Hawaiiensis, ii, pt. iv, Mollusca, 

 p. 352 (May 19, 1900). Type A. rugulosa Pease. 



The shell is rimate or imperforate, ovate-conic or oblong- 

 conic, the embryonic whorl varying from convex to flattened 

 and from nearly smooth to longitudinally striate ; later whorls 

 generally not variegated, covered with cuticle which is either 

 very thin, or (in Oahuan species) dark and partly deciduous. 

 Type A. rugulosa Pse. 



Amastrella occurs on all of the islands, except Lanai and 

 Maui, from Kauai to Hawaii. This wide distribution, to- 

 gether with the simplicity of the unspecialized shell, leads us 

 to regard the AmastrellaB as little-changed remnants of a prim- 

 itive Amastrine fauna, which, including also the Cyclamas- 

 trae, was spread over the entire group. 



Series of A. rugulosa. 



The shell is narrowly rimate or closed, ovate-conic, rather 

 roughly striate, dark-colored with a white streak behind the 



