144 Contributions to Indian Malacology. [No. 2, 
No. 18.—Unio Tueca., Bens. River Cane near Banda, Bundeleund. 
Benson, Ann. and Mag. Nat. Hist. 1862, 3rd Ser. X. 186. 
T have not seen this form. It belongs, according to Mr. Benson, 
to the Corrianus type of Unio marginalis. 
No. 19.—Unro macttentus, Bens. Choia Nuddy, near Bijnore, 
Rohilcund. 
Benson, Ann, and Mag. Nat. Hist. 1862, 3rd Ser. X. 187. 
A rather thin species resembling ceruleus, but with stout hinge 
teeth, resembling those of U. favidens. I am unacquainted with the 
type, but a very similar form is common in the Damuda and its 
tributaries in Bengal. 
No. 20.—Unto triempouus, Bens. R. Ramgunga, near Moradabad. 
Benson, Ann. and Mag. Nat. Hist. 1862, 3rd Ser. X. 190. 
A thick shell with large hinge teeth. A massive species which 
inhabits the Nerbudda, and the shells of which are found fossil 
associated with the bones of extinct mammalia in the gravels of the 
river valley, may be a variety of this species. I have never seen the 
type. 
No. 21.—Unto piaciosoma, Bens. River Cane near Banda, Bundel- 
cund. 
Benson, Ann. and Mag. Nat. Hist. 1862, 3rd Ser, X. 191, 
No. 22.—Unto tzvirostris, Bens. Near Chunar, in streams and 
tanks. 
Benson, Ann. and Mag. Nat. Hist. 1862, 3rd Ser. X. 191. 
No. 23.—Unto Pivax, Bens. Gungun stream, near Moradabad, 
Rohilcund. 
Benson, Ann, and Mag. Nat. Hist. 1862, 3rd-Ser. X. 192, 
The three abovenamed species appear all to be allies of U. favidens. 
They probably pass into each other. 
No. 24.—Unio Lzroma, Bens. Deccan? near Bombay. 
Benson, Ann. and Mag, Nat. Hist. 1862, 3rd Ser. X. 192. 
The locality of this shell is uncertain. I have no species from 
Western India which agrees with the description, 
