﻿STISTPSONIA 221 



Chamiji;Rlainia paviei (Modct). 



Shell subtriangularly orbicular, inequilateral, very slightly 

 convex, with faint, concentric strire and a thin yellow-green 

 epidermis ; beaks pointed, decorticated in the shells examined ; 

 anterior end rounded below, angled at its junction with the 

 dorsal line; dorsal wing rather high, angled behind; right 

 valve with two solid pseudocardinals and one curved lateral, 

 the hinge line being much narrowed and curved in front of it ; 

 nacre pale yellowish or whitish. 



Length 67, height 65, diam. 25 mm. 



Siam. 

 Unio pai'iei Morlet, J. de Conch., XXXIX, 1891, pi. vii, fig. 3. 

 Chamherlainia pmnei Simpson, Syn., 1900, p. ^82. 

 Chambcrlainia parici Rochebruxk, lUill. Mus. Hist. Nat., 1904, 



P- 463- 



Morlet does not give the number of the teeth in each valve, 

 but those of the right valve are shown in his figure. The shell 

 seems to be close to that of C. haincskina, but is more triangu- 

 lar in outline. 



Rochebrune, (1. c.) states that the series in the Museum 

 d'Histoire Naturelle show that this species is the young of 

 C. haiuesiana. 



Genus SIMPSONIA Rochebrune, 1904. 



Siinpso>iia Rochebrune, Bull. Mus. Hist. Nat., 1904, p. 46"^. 



"Shell elongate-ovoid ; very thick, heavy, with a slight pos- 

 terior wing; strongly sulcate ; beaks thick, obtuse, subcontig- 

 uous. their cavity quite deep ; ligament short, wide, subobtuse ; 

 pseudocardinals, two in the left valve, not large, compressed, 

 separated by a broad, concave, six-dentate interval, one in the 

 right valve, very large, quadrate, deeply bisulcate ; laterals 

 short, very heavy, one in the right valve, verv wide, high, 

 rounded above, two in the left valve, of equal length, very 

 short, acute, in the form of a letter X ; muscular impressions 

 deep, rugosely sulcate; pallial line deep, very wide in front." 

 (Rochebrune.) 



Type, Unio duclerci Rochebrune. 



