32 AMASTRA. 



common enough in some island faunas, but are remarkably 

 rare in the Hawaiian group, probably because such structures 

 are generally associated with aridity. In the Hawaiian group 

 arid conditions have come in so suddenly that there has been 

 extinction rather than adaptation of the snail fauna. 



A. ELLIPTICA Gulick. Vol. XXI, p. 204. 



Occurs in a Pleistocene or later deposit iy 2 miles west of 

 Kahuku, in a bluff of calcareous-sand rock, near the seashore 

 road, at a far lower level than the species now lives. 



Section PAEAMASTEA. Oahu. 

 A. MICANS (Pfr.). Vol. XXI, p. 210. 



Amastra erect a Pease, Vol. XXI, p. 305, of which one of 

 us has recently examined the type in the Pease collection, 

 Museum of Comparative Zoology, is identical with A. micans 

 (like pi. 37, figs. 5, 6, of Vol. XXI). It is to be deleted from 

 the list of Mauian species. 



Specimens of A. micans taken by Mr. Thaanum in Haleauau 

 are bandless, chamois or honey yellow to chestnut, often with 

 a fragmentary darker brown outer cuticle, and measure 15 x 

 7.5 to 17x8 mm. Those from Pukuloa are mostly a little 

 narrower, chestnut-colored with dark blue summit. 



On the western ridge of Popouwela we found about half 

 of the shells banded (frosti pattern), and very few white 

 under a thin, pale yellow cuticle, the upper part of the spire 

 flesh-colored. A. frosti is merely a mutation occurring in 

 some colonies of micans, and not a valid species or subspecies. 



A. SPIEIZONA (Fer.). Vol. XXI, p. 215. 



Add the synonym: Achatinella boetica Mighels, Jay's Cata- 

 logue Edit. 4, p. 214. 



The type locality of spiriznna was doubtless Helemano or 

 in that immediate neighborhood, and it is therefore exactly 

 equivalent to A. acuta Swains. It occurs in hybrid colonies 

 with the pattern called nigrolabris Smith. 



It is a notable fact that in the "Waianae range spirizona 

 has a different set of associates. I have not the material to 



