﻿226 CUIS'l'.VRIA 



trie ridges; ])lications of the posterior slope few and small; 

 posterior ridge very full and rounded on the earlier growth 

 hut fading out entirely in its later stages; posterior end nearlv 

 evenly rounded, very slightly pointed at the median line; cen- 

 ter of the disks smooth, the e|)idermis around the horder con- 

 centrically roughened, pale brownish in the center of the disks, 

 darker around the border : pseudocardinals wanting ; laterals 

 feeble, one in each valve ; beak cavities shallow with a row 

 of pits pointing towards the anterior base ; anterior scars ir- 

 regular ; posterior scars shallow ; nacre in the cavity of the 

 shell brownish, tinted with purple ; that of the posterior end 

 iridescent ; the nacre of the anterior end and base is verv solid 

 and milky-white ; prismatic border wide. 



Length 135, height without the wing 80, with the wing 95, 

 diam. 43 mm. 



Western Se-tchouan. China. 

 Dipsas occidentalis Hkudk, Conch. Fluv. Nank., IX, 1885, pi. 



LXVI. 

 Barbala occidentalis P.t-:tei-, Conch. Sam., TIT, 1890, p. 175. 

 Cristaria plicata (part), Simpson, Syn., 1900, p. 583. 



In the Synopsis I placed this species in the synonymy of C. 

 plicata. but additional study of the Cristarias and the examin- 

 ation of an author's specimen incline me to think that, though 

 very close to that species, it may be distinct. The beak sculp- 

 ture is much more feeble, as are the posterior plications, the 

 shell is more inflated, the posterior ridge is much fuller and 

 the nacre is brighter than in that species. The nacre around 

 the anterior border is very solid, more so than in any Cristaria 

 I know. Its outline is very much like that of plicata. 



Crtst.xria i?ku.ua (Morelet). 



Shell somew^hat trapezoidal, subsolid. slightly inflated, with 

 a high, widely rounded posterior ridge, which extends to the 

 extreme hinder point ; beaks low^, the umbonal region but little 

 inflated, with about six wide, low, concentric ridges ; posterior 

 slope with a few- folds, which show^ within and without ; an- 

 terior and posterior dorsal wings moderate, the upper dorsal 



