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BYOL. Xv, PROCEEDINGS OF THE NATIONAL MUSEUM. 429 
1892. 
Virginia to Florida, Blandingianus and Jewettii in Florida, columbensis 
in the Georgia streams that drain into the Gulf, and declivis from the 
latter State west to Texas, though these limits do not always hold good. 
I found thousands of the Blandingianus form in a little drain in the 
piney woods near Braidentown, which was always dry except during 
the rainy season, and its banks of slightly damp sand were full of 
dormant specimens. A number of these survived after lying out in the 
sun for months. 
Unio squalidus Lea. 
(Plate Lxx1, Fig. 4.) 
Unio squalidus Lea, Obs. x11, p. 26, pl. vu, Fig. 20, June 16, 1863, Neuse River, Raleigh, 
etc.; E. Emmons. 
Lea’s description of this shell seems somewhat contradictory, as he 
says it is smooth, and in his remarks that “it has that rough squamose 
epidermis which is generally found in the (obesws) group.” His speci- 
mens, though rough, are somewhat glossy. It is a stunted-looking 
species, less wide than most of the obesus, and rather rhomboid in out- 
line. In Mrs. Andrews’ collection, shells labeled “ Florida,” by Rugel, 
are, I think, of this species. One of Lea’s shells is faintly rayed. 
GROUP OF UNIO ROTUNDATUS. 
A small assemblage of more or less orbicular shells, which are often 
inflated and sometimes triangular. Unio Beadleianus on the one hand 
is nearly globose, while U. lenticularis is considerably compressed. 
Most of the species have a slight posterior ridge, though it is not con- 
stant; the epidermis varies from brown to chestnut; the hinge line is 
curved; cardinals somewhat ragge‘ and compressed, and the nacre 
ranges from a silvery white to purple. The species are confined, for the 
most part, to the streams emptying into the Gulf, being found from 
the Suwanee to the Brazos, and to the Tellico River, Tennessee. 
Unio succissus Lea. 
(Plate Lxx1, Fig. 5.) 
Unio succissus Lea, Obs. v, p. 31, pl. xx1, Fig. 32, Mar. 6, 1852. W. Florida; May. 
Le Conte. 
Unio cacao Lea (Plate LXx1, Fig. 6), Obs. vil, p. 26, pl. Lv1, Fig. 169, Mar. 10, 1859, 
Chocktahatchie R., Fla.; Maj. Le Conte. 
Lea has singularly confused this and allied species. He described it 
from a single specimen, a somewhat obovate, compressed shell, with 
an ill-defined posterior ridge, a chestnut epidermis and chocolate pur- 
ple iridescent nacre. It is rather solid in structure, and has quite a 
heavy hinge plate, with strong irregular cardinals and nearly straight 
laterals, slightly curved posteriorly. Subsequently he received an- 
other specimen from New Orleans, presented by Mr. Wheatley, which 
