6 
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. Plist. ser. 3, vol. 10 (1862), p. 192. 
Gungun Stream, near Moradabad, Rohilcund. 
Figured from the worn type lent by Mr. Benson. 
3. XT. favidens, var. plagiosoma.—U. plagiosoma, 
Benson, An. Nat. Hist. ser. 3, vol. 10 (1862), 
p. 191. 
River Cane, near Banda, Bundelcund. 
The beaks are eroded in the Bensonian type here 
figured. 
4. IT. 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. IT. erispisuleatus, Benson, An. Nat. Hist. ser. 3, 
vol. 10 (1862), p. 193.—Reeve, Conch. Icon. Unio, 
f. 262. 
Tenasserim ; Pegu. 
6. IT. 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 manuscript 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 ox favidens. 
PLATE XII. 
UNIO. 
1. U. 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 
caeruleus. 
2. U. Gcrbidoni, Eydoux and Souleyet, Guerin’s 
Mag. de Zool. 1838, pi. 118, f. 2. 
“ Coromandel.” 
Almost runs into cceruleus; in characteristic ex¬ 
amples, however, the anterior side is longer in propor¬ 
tion. It is not common. 
3. U. caeruleus, 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 Hooglily, &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. 
River 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. U. 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 cauruleus, &c., very 
closely. 
