﻿508 AI.ASMIIHINI'A 



Strol'hitiis nr.cr.cliiniiis Conkak, Tr. Ac. Xat. Sci. I'liila., \'I 



1853, P- 2^'3- 

 Ufiio S7i<aiiati<>c!isis Mam.icv, Test. Moll., 1S42, j). 211; Biv. 



Shells. 1843. P- 211, pi. XX 11 1, fii^. 30. 



Lea's material is in almost unrecoj^^nizable condition. Ihit 

 the National Museum possesses fine sets of the species from 

 Asheville, North Carolina, and from the North and South 

 Forks of the Cmnherland Fiiver. None of these specimens 

 have perfect beaks, hut one or two, which are less eroded than 

 the rest, seem to indicate that their sculj^ture consists of strong, 

 Avavy, slightly doubly-looped ridges. Old shells appear to be 

 uniform brown, but show^ the rays when held u]) to the light. 

 It is a larger, solider. more elongated shell than what I have 

 described as A. laricosa and is less solid and inflated, less trun- 

 cated behind and more biangulate than mari^inata. 



Subgenus Dui.i.ki.i.a Sim])son, tqoo. 



BuUcUo Simpson. Syn.. t^oo. ]>. ()y2. 



Shell thin, greatly inflated, somewhat triangular, with a high, 

 sharp posterior ridge; beaks very full, having exceedingly 

 strong, concentric .sculpture, extending well on to the disk : 

 pseudocardinals reflexed, compressed. 



Animal with the gills large, nearlv semicircular below, inner 

 the larger, united the whole length to the abdominal sac : man- 

 tle border with square spots. 



Type, Margaritana arcitia Lea. 



Ai.asmiik)nta ARcri,.\ (Lea). 



Shell subtriangTilar. thin, greatly inflatcfl. slightly inequi- 

 lateral, with very full, high beaks, their sculpture consisting 

 of a number of strong ridges running nearly parallel with the 

 growth lines. These extend well out on to the disk and they 

 are crossed by fine, wrinkled, radiating threads. In front of 

 and behind the regular sculpture there are radiating lirre. 

 Posterior ridge very high, angled, ending behind in a point 

 near the base; posterior slope truncated, with a low. radial 

 ridire : anterior end much narrowed, rounded, the beaks rising 



