TRAPEZOIDEUS I181 



Trapezoideus foliaceus (Gould). 



Shell long rhomboid, a little narrower in front, subsolid, 

 subcompressed or convex, inequilateral; posterior ridge feebly 

 double, there being often a third, faint ridge on the posterior 

 slope; dorsal outline lightly arched; posterior end obliquely 

 truncate above, somewhat biangulate below ; base line straight 

 or a little incurved ; anterior end rounded ; surface densely, 

 finely, concentrically sculptured ; beaks apparently low ; epider- 

 mis yellowish-green or yellowish-olive, in old shells usually 

 faintly clouded or widely rayed with green behind ; there are 

 two irregular, compressed, much-striated pseudocardinals in 

 each valve and two remote laterals in the left valve and one 

 in the right; beak cavities compressed but not deep; muscle 

 scars irregular ; nacre bluish-white, salmon-tinted in the cavi- 

 ties, of a soft, iridescent tint. 



Length 62, height 34, diam. 18 mm. 



Burma ; Cambodia. 

 Unio foliacca Gould, Pr. Bost. Soc. N. Hist., I, 1843, P- i4i- 

 Unio foliaceus HanlEy and Theobald, Conch. Ind., 1876, p. 



19, pi. XLii, fig. 3. — Anderson, Yunnan Exp., 1877, p. 900, 



pi. Lxxx, figs. 8-12. 

 Margaron (Unio) foliaceus- h^ a, Syn., 1852, p. 39; 1870, p. 62. 

 Trapezoideus foliaceus Simpson, Syn., 1900, p. 858. — Haas, 



Conch. Cab., Unio, 1912, pi. 32, figs. 3-4. 

 Unio peguensis Anthony^ Am. Jl. Conch., I, 1865, P- 35 1> pl- 



XXV, fig. 2. — SowERRY, Conch. Icon., XVI, 1868, pi. xcv, fig. 



519- 

 Margaron (Unio) peguensis Lea, Syn., 1870, p. 51. 



I am not positive that Gould's Unio foliaceus is the young 

 of Anthony's U. peguensis as Hanley and Theobald are, but 

 I am very strongly inclined to believe it. I have before me 

 two specimens from the Lea collection labeled Unio foliaceus 

 by Gould and presented by him to Dr. Lea. 



They are rather thinner than any specimens I have seen of 

 U. peguensis Anthony, and are not quite so strongly sculptured, 

 but they are smaller than any peguensis in the National 



