﻿CKISTAKIA 223, 



subcoiitiguous, placed at about 1/7 of the length; area small; 



lig"ament very long, thick, very black; interior pearly, tinged 



with pale rose. 



Length 240, height 169, diam. 75 mm." (Rochebrune. j 

 Type locahty, Riviere Claire between Vietri and Tuyen- 



Quas, Tonkin. 



Simpsonia demangei Rochhbrune, Bull. Mus. Hist. Nat., 

 1904, p. 465. 



Genus CRISTARIA Schumacher, 1817. 



Barbala Humphreys, Mus. Col., 1797. 

 Dipsas Leach, Zool. Miscellany, I, 1815, p. 119. 

 Cristaria Schumacher, Essai Nouv. Syst., 1817, p. 107. 

 Appius (Leach), Menke. Syn., 2d ed., 1828, ? p. 106. 

 Symphynota Lea (part), Tr. Am. Phil. Soc, 1830, p. 445. 

 Diamsotis Raejnesque, Cont. Monog., 1831, p. 7. 

 Dipsax VoiGT, Cuvier, Thierreich, III, 1834, p. 493. 

 Barbata vSowerby, Conch. Man., 1842, p. 81. 

 Clione Gistel, Nat. Sur. Hoh. Schule Bearb., 1848. 



Shell generally thin, elliptical, more or less winged poste- 

 riorly ; beaks rather low, sculptured with fine, somewhat doubly- 

 looped ridges at first, and later with coarse, low, concentric 

 bars, which are nearly parallel with the growth lines ; epider- 

 mis smooth, often somewhat rayed ; hinge teeth imperfect ; 

 pseudocardinals feeble or wanting — when present consisting of 

 a single compressed tooth in each valve ; laterals single, re- 

 mote, compressed, sometimes wanting in adult shells. 



Type, Dipsas plicatiis Leach. 



Subgenus Cristaria s. s. 



Shell large, thicker in front, strongly alate posteriorly, with 

 two or more slightly developed radial ridges on the posterior 

 slope and a row of plications above them ; hinge line regularly 

 curved ; dorsal scars forming a row running obliquely down- 

 ward and forward ; anterior scars often blurred, posterior 

 faint. 



