190 AMASTRA, OAHU. 



similar attenuated and biconcave outline near the apex. It is 

 similar to Leptachatina in the aspect of the shell owing to the 

 rapid growth of the three last volutions. The apex, however, 

 has not the blunted aspect of Leptachatina, nor the dispro- 

 portionate rate of growth between the nepionic and neanic 

 stages observable in that genus. The aperture is narrow 

 owing 'to the 'contraction of the last volution. The columella 

 is perforated, but the opening is not large and is almost closed 

 in some shells. The surface has coarse ridges of growth. The 

 nepionic stage has fine, transverse ridges of growth. The 

 characters in all respects are intermediate between cornea and 

 those of the more primitive shells of the Brevis series on the 

 island of Oahu and make it highly probable that this is a con- 

 necting species. 



Oa.hu : Fossil, near the base of Round Top, towards Rocky 

 Hill, where the Manoa road enters the valley back of Punahou. 

 Type no. 1749 C. M. Cooke coll. ; also 104689 A. N. S. P., and 

 in Boston Soc. coll. no. 13397. 



Hyatt's description is given above, and one of the types is 

 figured. The non-impressed suture and the sculpture are 

 other points of agreement between this species and A. cornea, 

 from which sub cornea differs chiefly by the more prominent 

 penultimate whorl, which gives the spire a wider shape than 

 that of A. cornea, approximating somewhat to the contour of 

 A. transversalis. The apical sculpture, very well preserved in 

 no. 13397 Boston Soc. coll. (from no. 1747 Cooke coll.), is 

 like that of A. cornea, the embryonic whorls being very finely 

 and closely striated, the striae arcuate. A. transversalis has 

 similar but straighter stria?. It is a fossil form, from a de- 

 posit of unknown age, probably Pleistocene, exposed in a road 

 cutting. 



Length 12.5, diam. 6.5, aperture 5.3 mm. ; 6% whorls. 



Length 10.8, diam. 5.3, aperture 4.5 mm. ; 6% whorls. 



If this species is really a member of the cornea series, it is 

 widely separated from its allies. 



34. A. EMULATOR n. sp. PI. 38, fig. 7. 



The shell is narrowly perforate, ovate-pyramidal, rather 



