Species of the Genus Unio. 193 



clined to be obsolete, the outer one is short, thin, and promi- 

 nent; those of the right valve are divaricate, the outer one thin, 

 and the inner thicker, erose, and prominent at the end. The 

 anterior cicatrices are distinct, the posterior confluent, the apical 

 ones run under the inner cardinal tooth. The cavity of the 

 beaks is shallow. There are slight indications of rugae on the 

 posterior slope. The valves are open posteriorly. The elevated 

 portion of the posterior slope is broad and flattened. It has 

 considerable resemblance in form to U. navigioliformis, Lea, but 

 is more perpendicularly truncate posteriorly, has very different 

 teeth, and the lateral ones are shorter in comparison. It differs 

 altogether from U. Shurtleffianus, Lea, from the Dekhan, in its 

 very transverse form, the position of the beaks, and the colour 

 of the epidermis. 



This pod-shaped species is very distinct from all the shells of 

 the caruleus type, both in form and surface. I mislaid my note 

 of its habitat ; but, from various circumstances, I have reason 

 to believe that it was sent to me by Dr. Jerdon from the 

 Dekhan. 



12. Unio crispisulcatus, B., n. sp. 



U. testa transverse subovata, subineequilaterali, antice rotundata, 

 postice superne descendente, leviter angulata, demum obtuse an- 

 gulata, crassiuscula, compressiuscula ; disco convexiusculo, minu- 

 tissime radiatim rugoso-costulato, costulis nonnullis acute divari- 

 catis, posterioribus latioribus ; umbonibus prominentibus, con- 

 tiguis, apicibus acutiusculis ; epidermide luteo-olivacea, postice 

 fuscata, bic illic nonnunquam viridescente ; dentibus cardinalibus 

 utriusque valvee duplicibus, lamellatis, lateralibus obliquis, modice 

 elongatis, valvee sinistree duplicibus : margarita ceeruleo-albida, 

 iridescente. 



Long. 28, lat. 45, diam. 16 mill. 



Habitat in rivulo Bangong, prope Thyet-Myo, regionis Burmanicee. 

 Collegit W. Theobald. 



The anterior cicatrices are distinct, the posterior confluent, 

 the apical ones above the moderate angular cavity, and running 

 under the cardinal tooth. 



The delicate sculpture over the whole disk of this shell is 

 peculiar. In form it does not approach any Gangetic type. 



13. Unio Pugio, B., n. sp. 



U. testa transverse elongato-triangulari, lingueeformi, valde insequi- 

 laterali, compressiuscula, crassa, antice brevissima, subito descen- 

 dente rotundata, postice sensim angustiore, cuneiformi, demum 

 acuminata, margine dorsali recto, ventrali convexiusculo, postice 

 ascendente ; umbonibus late planatis, laevibus, prominentibus, 

 carina umbonali subito obtuse angulata, area interjacente versus 

 cardinem descendente ; disco subplanulato, lseviusculo, substriato ; 



Ann. fy Mag. N. Hist. Ser. 3. Vol.x. 14 



