PSEUDODOtf. 153 



Long. 59, lat. 140, diam. 32 mm. 



Hob. Salwen River, Burma; Tenasserim River (Lid. Mus. 

 Coll). 



288. Pseudodon (Pseudodon) nicobaricus (Morch). 



Pseudodon (Pseudodon) nicobaricus (Morch) ; Simpson, Washington, 

 D.C., Smiths. Inst., Nat. Mus. Proc. xxii, 1900, p. 838. 



Alasmodonta (subg. ?) nicobarica, O. Fabiicius ; Morch, J. Conchyliol., 

 Paris, xx, 1872, p. 327. 



Original description : Testa irregulariter ovalis, convexiuscula ; 

 strise incrementi irregulares ; diraidium testae marginem versus 

 olivaceum, fasciis obscurioribus, radiis numerosioribus, obsoletis, 

 obscure viridibus. Intus argeutea, postice iridescens. Umbones 

 plani, erosi, antice siti ; margo dorsalis parum arcuatus, (inargo) 

 anticus rotundatus, angustior, (margo) ventralis antice et postice 

 sat arcuatus, medio leviter inflexus, (margo) post, angustus leviter 

 reflexus. Dentes cardinis fere oinnino evanescentes, dens lat. 

 post, linearis obsoletissimus. 



Anodonta zollingeri, Mousson (Java, p. 96, t. 18, fig. 1), affinis, 

 sed species Fabricii differt : margine ventrali arcuato, postice 

 subito ascendente, nee non margine dorsalis declivi, baud arcuato. 



Hob. Nicobar Islands (0. Fabricius). 



The species was described from a single specimen without figure 

 or dimensions being given, it does not seem to have come to light 

 again at any time. 



Section BINEURUS. 



Bineurus, Simpson, Washington, D.C., Smiths. Inst., Nat. Mus. 

 Proc. xxii, 1900, p. 839. 



TYPE, Monocondylcea mouhoti, Lea, from Cambodia and Siain. 



Range. Cambodia; Siam ; Perak ; Burma. 



Original description : Shell elongate rhomboid, thin, rounded in 

 front, widely and feebly biangulate behind, having two or more 

 raised radiating lines on the posterior slope, which is somewhat 

 obliquely wrinkled ; beaks low ; surface finely, irregularly, con- 

 centrically grooved ; epidermis olive ; teeth smooth, compressed ; 

 nacre bluish. 



Animal unknown. 



289. Pseudodon (Bineurus) ava (Theobald). 



Pseudodon (Bineurus) ava (Theobald) ; Simpson, Washington, 



D.C., Smiths. Inst., Nat. Mus. Proc. xxii, 1900, p. 839. 

 Monocondylcea ava, Theobald, J. A. S. B. xlii, 1873, pt. 2, p. 209, 



pi. 17, fig. 15. 



Original description : Testa oblonga, solidiuscula, antica rotun- 

 data, postice curvatim truncata. Margine ventrali recto ; liga- 

 mentali convexo. Umbonibus decorticatis. Epidermide picea in 

 junioribus luteo-flavescente lineis tenuibus obscure radiatim 



