﻿220 CIIAMr.i:RI.AINIA 



Unio haincsianus Lea, Pr. Ac. i\. Sci. Phila.. YTII, 1856, p. 



92; Jl. Ac. N. Sci. Phil., III. 1857, p. 289. pi. xxi, fijj. i; 



Obs., VI, 1857. p. (), pi. XXI. fi.c:. 1. — SowivRiiv, Conch. Icon., 



XVI, 1866, pi. xi.vii. fiij. 254. 

 Margaron (Unio) haincsianus Lka. Svn., 1870, j). 28. 

 Chamberlainia hainesiaua Simtsox, Syn.. hjoo, p. 582. 

 Unio impcriaUs MoRrci.irr. Rev. ct Alatj. Zool, XI\\ 1862, p. 



480. 



The type consi.sts of a sin,y:le valve of a younu: indivichial. 

 U. impcrialis, accordin^e: to its antlior. attains a size of 142 mm. 

 in heig-ht. 192 mm. in length, and yy mm. in diameter. I have 

 seen a very fine specimen in the Frederick Stearns collection 

 6 inches hig-h and 8 in length. Tt is one of the most magnifi- 

 cent Naiades in the world. 



CnAMUKRF.AiNiA PAVONiNA Rochebrune. 



"Shell thick, heavy, siibtrigonal, inequilateral, slig-htly com- 

 pressed, slig-htly g-aping; olive-brown, siibshining- ; deeplv con- 

 centrically sulcate, sulci here and there subfoliaceous ; dorsal 

 margin oblique ; anterior round, obtusely subrostrate ; poste- 

 rior abruptly truncate, sulbalate, faintly triangular : basal mar- 

 g'in broadly convex ; beaks eroded, subcontiguous, rounded, 

 situated at about one-fifth of the length ; disk flattened, with 

 broad, undulating, slightly spreading plications ; ligament 

 heavy, short, curved, somewhat covered : interior whitish-blue, 

 more or less pearly, deep coppery and iridescent posteriorlv. 



Length 175, height 134, diam. 65 mm." (Rochebrune.) 



Type locality, Battambang, Province of Salabu^\^ Siam. 

 Chamberlainia pai'onina Rochkiirune, r>ull. Mus. Hist. Nat., 



1904, p. 464. 



"This form, while close to Chamberlainia hainesiajia. dififers 

 by its less trapezoidal, more ovoid shape, by the more rounded 

 anterior end, by the greater convexity of the basal margin, by 

 the aliform expansion of the posterior margin being more tri- 

 ang^ilar and less rounded, the more anterior beaks, which are 

 less acute, bv the pscudocardinals stronger, more massive pro- 

 portionally and more deeply crenulate and finally by the longer 

 and more prominent teeth." 



