208 W. Theobald — Descriptions of New Species of Unionidce. [No. 4, 



and U. onandelayensis constitute a natural little sub-group of osculant spe- 

 cies at once distinct, but connected and sufficiently distinguishable from any 

 of the ordinary Indian types. I have not, however, felt justilied in separat- 

 ing them from the great Indian " corrugatus^^ group in my forthcoming 

 catalogue of Indian shells. 



Unio mandelatek"sis, n. s., PI. XYII, Fig. 2. 



Testa cuneate suhtriangulari, onargine ligamentali recto, ventrali, 

 rotundato ; valde incequilaterali : antice Icevi, umhones versus leviter corru- 

 gatd ; postice ah umhonihus usque ad angulam posterior em fortiter plicato- 

 corrugatd. JEpidermide IcBvi, tenui, suhpolitd, glaucd sive viridi-flavd, lineis 

 plurimis radiantihus ohscure pictd. Umhonihus decorticatis, granulosis 

 lineis duohus pallidis 5-6 muricate spinigeris, ornatis. Lineis ad marginem 

 tendentihus, spinis vero vice ad medium valvos attingentihus. Detitibus sicut 

 in precedente. 



Hah. prope 3Iandelay, regno JBirmanico. 



Lat. 53, alt. 40, crass. 31 mm. 



In only one specimen have I seen the muricate spines descend below 

 the centre of the valves, but the pale linear bands whereon they stand 

 usually descend to the margin. 



The peculiar sculpturing of TI. hurmanus is also seen in this species 

 though less strongly marked and though sometimes carried over a good por- 

 tion of the valves, yet is usually most pronounced on the posterior slope. 



Ui^io Fedde:^^!, n. s., PL XV., Fig. 3. 



Testa quadrato-ovali, concentrice sulcata, antice gihhose rotundatd, pos- 

 tice dilatatd, suhtruncatd ; parum incequilaterali. Lmhonihus decorticatis, 

 liaud prominentihus. Mpidermide Icevi, suhpolitd, viridescentiflavd. Denti- 

 hiis cardinalihus lamelliformihus, striatis ; in valvd dextrd singulo, serrato, in 

 sinistra geminis triangular ihus, striatis et serratis. JVacred ccerulescenti- 

 alhidd. 



Hah. in Peemgungafluvio, Indice centralis. Teste F. Fedden, 



Lat. 40, alt. 29'5, crass. 19 mm. 



This very peculiar and marked form which somewhat recalls by its out- 

 line the American TI. securis, seems a rare species and was collected spar- 

 ingly among numbers of fine specimens of TT. wyngungensis, Lea, in Cen- 

 tral India by my colleague Mr. Fedden after Avhom I have named it. 

 It falls naturally within the great " corrugatus'^ group, though there 

 are few better marked varieties than it. 



Unio gowhattensis, n. s., PI. XVII, Fig. 4. 

 Testd quadrato-ovatd, antice rotundatd, postice declive truncatd, margine 

 ventrali recto. Umhonihus decorticatis. Mpidermide Jiavescente, postice 



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