194 MELANIIDA. 
Genus I0, Lea. 
Philos. Trans, IV, 1832, type Io fluviatilis, Say; fide Brot., Sub-Genus 
of Pleurocera, 
1. Io fluvialis. 
Fusus fluvialis, Say, J. dead. Nat. Sez. V, 1825. 
var. inermis. 
Io inermis, Anthony, P. Acad. Nat. Sei., 1860. 
2 Tennessee; coll, Prof. W. Newcomb. 
2. Io spinosa. 
-Io spinosa, Lea, Philos. Trans. V, 1834, Kolston Rv. [Virginia]. 
2 Tennessee; coll. Prof. W. Newcomb. 
Genus PLEUROCERA, Rajfinesque. 
J. de Phys. Brux. 1819 [no type recorded];=Cerithasia, Swainson,’ 1840, 
type C. sulcata;=Trypanostoma, Lea, 1862, type Mel. canaliculata, 
Say ;=Strepoma, Auct. [as of Rafin.]. 
Fide Tryona sub-genus of Io. 
1, Pleurocera canaliculata. 
Melania canaliculata, Say, J. dead. Nat. Sci., IT, 1821. 
4 Indiana; coll, I. Lea, Esq. [Asiat. Soc. Bengal]. 
2 Ohio; coll. Prof. W. Newcomb. 
3 Coosa Rv., Alabama; coll. Revd. E.R, Beadle [labelled “Jf, pon- 
derosa’”}. 
2. Pleurocera ponderosa. 
Melania ponderosa, Anthony, P. Acad, Nat. Sri. 1860. 
5 Indiana; ex c. Dr. T. Oldham. 
3. Pleurocera filum,. 
Melania filum, Lea, Philos. Proe. IV, 1845, Alabama. 
8 Tennessee; coll. Prof. W, Newcomb. 
