150 UNIONID^E. 



285. Pseudodon (Trigonodon) peguensis (Anthony). 



Monocondylcea peguensis, Anthony, Am. Journ. Conch, i, 1865, 



p. 205, pi. 17, fig. 2. 



Margaron (Monocondylcea) peguensis, Lea, Syn. 1870, p. 73. 

 Pseudodon crebristriatnm var. peguensis, H. & T., C. I. 1876, p. 5, 



pi. 9, fig. 5. 

 Pseudodon (Trigonodon) crebristriatus var. peguensis, Simpson, 



Washington, D.C., Smiths. Inst., Nat. Mus. Proc. xxii, 1900, 



p. 835. 



Original description: Shell smooth, rhombic-ovate, inequilateral, 

 somewhat inflated, sub-biangular behind ; substance of the shell 

 thick; beaks rather prominent, eroded, but apparently not undu- 

 lated ; ligament short, thin ; epidermis dark brown or nearly 

 black, smooth over the umbones and on the anterior portion of 

 the shell, but having the sub-truncate posterior portion nearly 

 covered with distinct corrugated folds, more prominent near the 

 hinge margin ; cardinal teeth prominent, curved and slightly 

 bilobed, particularly in the right valve; anterior cicatrices con- 

 fluent ; dorsal cicatrices deeply impressed, placed in a curved line 

 under the beaks ; nacre light salmon-colour and very iridescent. 



Long. 57, lat. 81, diam. 33 mm. 



Hob. Pegu. 



Yar. crebristriatus (Anthony). 



Monocondylcea crebristriata, Anthony, Am. Journ. Conch, i. 1865, 



p. 205, pi. 18, fig. 1. 

 Trigonodon crebristriata, Conrad, Am. Journ. Conch, i, 1865, 



p. 233. 

 Unio crebristriatus, Sowerby, Conch. Icon, xvi, 1868, pi. 95, 



fig. 517. 



Margaron (Monocondylcea) crebristriata, Lea, Syn. 1870, p. 72. 

 Pseudodon crebristriatus, H. & T., C. I. p. 5, pl/9,fig. 3. 

 Unio vondembmchi, Sowerby, Conch. Icon, xvi, pi. 95, fig. 518. 

 Pseudodon (Trigonodon) crebristriatus, Simpson, Washington, D.C., 



Smiths. Inst., Nat. Mus. Proc. xxii, 1900, p. 835. 



Original description. Shell rhombic, strongly striate, very 

 inequilateral, depressed, bi-angular behind ; substance of the shell 

 rather thick ; beaks not prominent, eroded, having no indication 

 of any undulations at the tip ; epidermis light brown, with occa- 

 sionally broad green rays on the posterior slope ; the umbones 

 and, indeed, the surface is covered with crowded, fine, crenulose 

 striae, which, on the posterior slope, are crossed at right angles 

 with prominent, regular folds ; cardinal teeth prominent, erect, 

 bilobed in the left valve ; anterior cicatrices deeply impressed, 

 distinct ; posterior cicatrices confluent and indistinct ; dorsal 

 cicatrices small, but distinct, and placed at the base of the pro- 

 minent tooth in the left valve, while in the right valve they are 



