APPENDIX. 383 
curved, compressed, extremely inequilateral, rather thick (not solid), 
obliquely and very bluntly subbiangulated in front, narrowly rounded 
behind, of an uniform brownish black, adorned with numerous sub- 
angular isolated tubercular divergent undulatiens upon, and in front 
of, the broad and rounded (yet not elevated) umbonal ridge, beyond 
which the surface is abruptly flattened, closely and coarsely g grained 
(or finely tuberculated), and then merely wrinkled by the lines of 
growth; ventral edge retuse behind the middle; umbones not at "7 
prominent : inside silvery ; ; cardinal teeth small, yet strong. 2.. 
Australia. 
Unto Hemet (t. 24, f. 3), Conrad, Mon. U. p.93, t.51. Oblong- 
elliptical, very imequilateral, rounded behind, bluntly subcuneiform 
(when adult) in front, moderately strong, compressed, of an uniform 
pitch-brown, concentrically wrinkled, and studded with somewhat 
divergently disposed tubercular elevations on the ordinary site of the 
umbonal ridge; ventral edge retuse in the middle; ligamental edge 
convex ; umbones eroded, scarcely projecting above the dorsal line ; 
ligament long, tawny; inside white; cardinal teeth solid; lateral 
crenulated. 14...31. Louisiana. 
A. B. **** Non-symphonote smooth or concentrically sulcated 
Uniones proper. 
Unio Srcvuxws (t. 20, f. 19), Swainson, Malac. p. 282, f. 58.  Pro- 
duced- -oblong, very inequilateral, thick, subyentricose, yellow ish olive 
arranged in lighter and darker concentric shades, not rayed, smooth 
(except the lines of growth); ventral edge retuse in the middle, rising 
in an oblique curve posteriorly : anterior extremity very bluntly sub. 
cuneiform, ligamental edge subparallel with the ventral; hinder side 
occupying two- -sevenths only of the total measurement, its extremity 
subangulated dorsally, rounded ventrally; no conspicuous umbonal 
ridge; umbones little raised, the corrugations indistinct ; nacre white, 
umbonal cavity tolerably ample; the inner cardinal teeth large, solid, 
jagged. 13...34. Sicily. The specimen described came from Lake 
Leontini, and was, I believe, one of Swainson’s. Lea, perchance 
correctly, refers the species to U. pictorum. 
Unio suBPLANUs (t. 21, f. 16), Conr. Mon. U. t. 41, f.1. Semi- 
rhombic-oyal, moderately imequilateral, subbiangulated in front, 
rounded behind, thickish, subcompressed, pitch- brown, not rayed, 
smoothish; umbonal ridge inconspicuous; ventral edge arcuated 
behind, subparallel in front to the scarcely convex anterior dorsal 
edge; umbones eroded, not prominent; cardinal teeth strong, tri- 
angular; lateral teeth elongated. 14.,.2. Viryinia. 
