190 Mr. W. H. Benson on Indian and Burmese 



Malabar My a radiata, Ch. (not the American shell described by- 

 Lamarck and others), as there are traces of obsolete radiate striae 

 over the whole disk. It is 21 mill, long, 30 broad, and 12 mill, 

 in diameter, and in form approaches the figure of Mya radiata 

 in Wood^s Index. 



6. Unio SmaragditeSy B., n. sp. 



U. testa transverse ovato-rhomboidea, inaequilaterali, crassiuscula, 

 tumida, antice rotundata, postice alata, recta, turn valde declivi, 

 demum subangulata, margine ventrali convexo ; disco Isevigato, 

 polito, vix striatulo, sub epidermide pulchre viridi tenuissima ob- 

 scure radiata albo, margine lutescente ; umbonibus prominentibus, 

 apicibus approximatis, subdecorticatis, margaritaceis, breviter et 

 minute radiato-sulcatis ; lunula angusta, elongata, transverse ru- 

 gata ; ligamento subelongato ; carina umbonali prominente obtusi- 

 uscula, areola versus apicem depressiuscula, viridi obscure radiata ; 

 dentibus cardinalibus duplicibus, subangustis, rugosis, lateralibus 

 curvatis elongatiusculis, valvae dextrse simplicibus, sinistrse dupli- 

 cibus, nonnunquam subtriplicibus : margarita albida, nonnunquam 

 luteo tincta. 



Long 31, lat. 42, diam. 20 mill. 



Habitat in fluvio Berhampooter, regionis Assamensis. 



Remarkable for the smoothness of the beautiful green epi- 

 dermis, vrhich is very thin, and, when rubbed off, exhibits a 

 plain white colour, not nacreous, underneath. The anterior 

 cicatrices are confluent, the posterior nearly distinct, the apical 

 ones situated under the cardinal teeth. Cavity of beaks very 

 deep ; a few rugae cross the striae on the posterior slope. In 

 general characters it approaches most nearly to the Jellinghy 

 variety {Delta) of U.favidens, which has a more tumid ovate form, 

 a regular, sulcate, olivaceous surface, longer and distinctly angu- 

 late-flexuous umbonal furrows, and a broad lunule. 



I received this shell from Colonel Jenkins. 



7. Unio triemholuSy B., n. sp. 



v. testa oblique rhomboidali, subtrigona, transversa, inaequilaterali, 

 crassa, antice brevi rotundata, postice subalata, descendente, de- 

 mum angulata, obtusa, margine ventrali convexo ; disco transverse 

 plicato et striato, piceo-nigrescente ; umbone tumido, gibboso, 

 versus apices remotos obtusos decorticates iridescentes radiato- 

 sulcato, carina umbonali obtusa ; dentibus cardinalibus crassissimis, 

 corrugatis, lateralibus obliquis, valva dextrse duplicibus, sinistrse 

 triplicibus : margarita albida vel colore salmonis tincta. 



Long. 47, lat. 67 y diam. 27 mill. 

 „ 45, „ 62, „ 27 „ 

 „ 44, „ 63, „ 30 „ 



Habitat in flumine Ramgunga, prope Moradabad. 



Smaller varieties of the more trigonal as well as of the oblique 



