556 PROCEEDINGS OF THE ACADEMY OF [Nov., 
I believe Plewrobema mytiloides (U. mytiloides) Raf. Monogr. 
(1820) p. 313, No. 51, Pl. 82, figs. 8, 9, 10, is also P. clava Lam., but 
unfortunately the type is not in the collection here. 
Pleurobema cyphia Raf. 
Obliquaria cyphya (U. cyphia) Raf. Monogr. (1820), p. 305, No. 29. 
The type is A. N. S. P. Coll. No. 20,239, from the Ohio River. 
Length 83, height 58, diam. 36 mm. 
This is Pleurobema cesopus Green (1827) of Simps. Synops., p. 
764, Descr. Catal., p. 806. 
Quadrula costata Raf. 
Amblema costata (Unio costata) Raf. Monogr. (1820), p. 315, No. 57, Pl. 82, 
figs. 13, 14. 
The type is A. N. 8S. P. Coll. No. 20,246, from small creeks in 
Kentucky. 
Length 66, height 53, diam. 24 mm. 
This is Quadrula undulata Bar. (1823) of Simps. Synops., p. 569, 
Descr. Catal., p. 819. 
Quadrula cylindricus Say. 
Unio solenoides (Elliptio solenoides) Raf. Monogr. (1820), p. 298, No. 138. 
The type is A. N. 8. P. Coll. No. 20,204, from the Ohio River. 
Length 73, height 32.5, diam. 27 mm. 
This is Quadrula cylindricus Say (1816) of Simps. Synops., p. 773, 
Descr. Catal., p. 832. 
Quadrula metanevra Raf. 
Obliquaria metanevra (Unio metanevra) Raf. Monogr. (1820), p. 305, No. 30, 
Pl. 81, figs. 15, 16. 
The types are A. N. 8. P. Coll. No. 20,238, from the Ohio River. 
Length 87, height 68, diam. 51 mm. 
Length 31, height 27, diam. 12 mm. 
This is Quadrula metanevra Raf. of Simps. Synops., p. 774, Deser. 
Catal., p. 834. 
Quadrula quadrula Raf. 
Obliquaria quadrula (Unio quadrula) Raf. Monogr. (1820), p. 307, No. 35. 
This shell is A. N. S. P. Coll. No. 20,224, from the Salt River. 
Length 60, height 49, diam. 31 mm. 
This is Quadrula lachrymosa Lea (1828) var. asperrima Lea (1831) 
of Simps. Synops., p. 776, Deser. Catal., p. 842. 
Quadrula pustulosa Lea. 
Obliquaria retusa (Unio retusa) Raf. Monogr. (1820), p. 306, No. 32, Pl. 81, 
figs. 19, 20. 
The type is A. N. 8. P. Coll. No. 20,220, from the Green River, 
one valve. 
