184 UNIONID^E. 



double in the right ; lateral teeth long, thin, bladed and nearly 

 straight ; anterior cicatrices distinct; posterior cicatrices confluent ; 

 dorsal cicatrices situated nearly in the centre of the cavity of the 

 beaks ; cavity of the beaks exceedingly shallow ; nacre pearly 

 white and iridescent It closely resembles the U. margi- 

 nalia of Lamarck, but differs from that species in being more 

 transverse, in the beaks being more retuse, in the dorsal line 

 being nearly straight, and in its not being possessed of a light 

 border along the margin. The cardinal teeth are remarkably thin, 

 and form nearly a line with the lateral teeth." 



Subsp. generosus (Gould). 



Unio generosus, Gould. Proo. Boston Soc. Nat. Hist, ii, 1847, 

 p. 220 ; Otia Conch. 1862, p. 210 ; H. & T., C. I. 1876, p. 22, 

 pi. 46, fig. 4 ; Pastel, Conch. Sam. iii, 1890, p. 153. 



Margaron (Unio) generosus, Lea, Syn. 1870, p. 29. 



? Unio lamellatus, Sowerby, Conch. Icon, xvi, 1868, pi. 94,iig.5H. 



Lamellidens generostts (Gould), Simpson, Washington, D.C., Smiths. 

 Inst., Nat. Mus. Proc. xxii, 1900, p. 857. 



Original description : Testa magna, solida, transversa, oblongo- 

 ovata, inequilateral!, antice rotundata et angustata ; postice ob- 

 liquata, subrostrata, ad apicem truncata ; margine ventrali arcuata, 

 dorsali recta, abscendente ; umbonibus contiguis hand elevatis ; 

 valvis subtumidis radiatim substriatis, postice subcostatis, epider- 

 mide fuliginosa, disco nitido : dentibus remotis ; cardinalibus 

 elongatis, obliquis, laminatis : margarita alba vel salmonacea 

 limbo iridescente. 



Long. 64, lat. 95-5, diam. 38-25 mm. 



Hob. Newville, Tavoy (Mrs. Vinton) ; specimens in the Indian 

 Museum are labelled respectively Myadong, Upper Burma 

 (Anderson), Mandalay (Annandale), and Bhamo (J. Coyyin 

 .Brown). 



Subsp. jenkinsianus (Benson). 



Unio jenldnsiamis, Benson, A. M. N. II. x, 1862, p. 185 ; H. & T., 

 C.I. 1876, p. 19, pi. 41, fig. 4; Pastel, Conch. Sam. iii, 1890, 

 p. 155. 



Lamellidens jenMnsianus (Benson), Simpson, Washington, D.C., 

 Smiths. Inst., Nat. Mus. Proc. xxii, 1900, p. 857. 



Original description : Testa transverse elongata, subacuminato- 

 ovata, valde insequilaterali, tumida, crassa, antice brevi rotundata, 

 postice elongata, minim e alata, superne sensim descendente, 

 demum angusta. . obtusa ; margine basali antice convexiusculo, 

 postice subrecto ; ligamento brevi ; disco valde tumido, transverse 

 plicato ; epidermide picea, versus marginem ventralem olivacea ; 

 umbonibus leviter convexis, decorticatis, apicibus obtusis ; dentibus 

 arcuatim sitis, crassiusculis, erosis, cardinalibus elongatiusculis. 



