CONCHOLOGIA INDICA. 



PLATE XI. 



UNIO. 



1. U. favidens, Benson, An. Nat. Hist. ser. 3, 

 vol. 10 (1862), p. 188, for Glean. Sci. Calcutta, 

 vol. 1, pi. 7, f. 1 (without name). — Reeve, Conch. 

 Icon. Unio, f. 131. 



Sunderbund, Bengal. 



The species was not actually described until Septem- 

 ber, 1862. 



2. U. favidens, var. pinax. — U. pinax, Benson, An. 

 Nat. Hist. ser. 3, vol. 10 (1862), p. 192. 



Gungun Stream, near Moradabad, Eohilcund. 



Figured from the worn type lent by Mr. Benson. 



3. U. favidens, var. plagiosoma. — U. plagiosoma, 

 Benson, An. Nat. Hist. ser. 3, vol. 10 (1862), 

 p. 191. 



Eiver Cane, near Banda, Bundelcund. 



The beaks are eroded in the Bensonian type here 

 figured. 



4. U. Sikkimensis, Lea, Proc. Philad. 1859, p. 151; 

 Obs. Unio, vol. 7, p. 69, pi. 39, f. 131.— Reeve, 

 Conch. Icon. Unio, f. 400. 



Sikkim. 



This is in a better condition than Mr. Hanley's 

 original type of the species. 



5. U. erispisulcatus, Benson, An. Nat. Hist. ser. 3, 

 vol. 10 (1862), p. 193. — Reeve, Conch. Icon. Unio, 

 f. 262. 



Tenasserim ; Pegu. 



6. XJ. trirostris, Benson (not Reeve), in Hanley's 

 Phot. Conch, pt. 1 (1862). 



Moradabad. 



This well marked form was distributed by Mr. 

 Benson as his U. trirostris (a name, like very many 

 other of his maniiscript species) never actually published 

 by himself The specimen delineated in the Photo- 

 graphic Conchology had been previously sent to Dr. 

 Lea, who regarded it as new to science. It may pos- 

 sibly prove a mere variety of triembolus or favidens. 



PLATE XII. 

 UNIO. 



1. TJ. pachysoma, Benson, An. Nat. ser. 3, vol. 10 

 (1862, Sept.) : separate, p. 3. 



Berhampooter River, Assam. 



A much more solid and rare shell than the allied 

 cceruleus. In England the only known specimens 

 are in the collections of Benson and Hanley. The 

 Calcutta specimen referred to by Benson is merely a 

 casruleus. 



2. U. Gerbidoni, Eydoux and Souleyet, Guerin's 

 Mag. de Zool. 1838, pi. 118, f. 2. 



" Coromandel." 



Almost runs into cwruleus ; in characteristic ex- 

 amples, however, the anterior side is longer in propor- 

 tion. It is not common. 



3. IT. esenileus, Lea, Trans. Amer. Phil. Soc. vol. 4 

 (Obs. on U. vol. 1, p. 105) pi. 13, f 25.— Hanley, 

 Recent Bivalve Sh. p. 194, pi. 20, f. 49.— Reeve, 

 C. Icon. Unio, f. 230. 



River Hooghly, &c. &c. 



4. U. Gerbidoni, variety, Eyd. and Soul. 



5. U. theca, Benson, An. Nat. Hist. ser. 3, vol. 10 

 (1862, Sept.) : separate, p. 3. 



Eiver Cane, near Banda, Bundelkund. 



Our drawing is taken from the unique example in 

 Mr. Benson's collection. The specimen seems scarcely 

 mature, and bears some small resemblance to the young 

 of one of the marginalis group. 



6. TJ. leioma, Benson, An. Nat. Hist. ser. 3, vol. 10 

 (1862, Sept.), p. 192 : separate, p. 9. 



Near Bombay. 



We have figured two shells, one the aged and 

 eroded type of Benson, the other with the apical 

 sculpture perfect. It approaches cseruleus, &c., very 

 closely. 



