j 
412 NOTES ON FLORIDA UNIONID—SIMPSON. 
tion of this species, as is shown in his collection, where the most di- | 
verse forms from Canada, New England and the Middle States are 
placed by him under the name of U. complanatus. But he seems to 
have fixed its southern limit with some rare exceptions somewhere — 
about the State of Virginia, and has applied specific names to every 
variation found south of that. One can almost exactly duplicate in his _ 
immense series of complanatus such forms as roanoakensis, savannah- 
ensis, Postellii, neusensis, Hallenbeckii, napeanenssi, hopetonensis, and a 
dozen others, and the conviction becomes strong with any one who at- 
tempts to study or name the members of this puzzling group that ifthe 
diversified forms in the more northern States are mere variations of 
one species, most of those in the South are nothing more. There is an 
immense amount of this material, numbering thousands of specimens, 
in Dr. Lea’s collection and among his duplicates, contributed largely 
by Dr. Emmons, C. M. Wheatley, Girard Hallenbeck, Dr. Lewis, J. 
Postell, Bishop Elliott, and Dr. Barrett. The accompanying notes, the 
hames written on the shells and erased, and the controversies among 
these earnest students of a past generation concerning their proper 
identification, show how hopeless was the task of attempting to satis- 
factorily determine these varying and puzzling forms. 
It may be said in general terms that the species of the group are 
wide and rhomboidal, with usually a well developed posterior ridge, 
are somewhat compressed, with an epidermis varying from smooth and 
shining to squamose, and in color range from tawny yellow through 
greenish to black, either with or without rays. The nacre is not often 
iridescent, and varies from white or yellowish to deep purple. 
Unio hopetonensis Lea. 
(Plate Lil, Fig. 3, Plate Lin, Fig. 1.) 
Unio hopetonensis Lea, Obs. 11, p. 29, Pl. 1x., Fig. 24, Feb. 5, 1836. Hopeton, Ga.; 
Prof. Shepard. 
Dr. Lea deseribed this species from a young individual (diameter, 9; 
length, 1.7; breadth, 5.4 inches), which but imperfectly showed the — 
characters of the adult shell. I have been strongly tempted to place 
Unio dariensis in the synonomy, for though selected specimens of the 
latter differ in a marked degree from the former, yet among the large 
amount of material that has passed under my hands there are examples 
which may as well be placed with the one as the other. The species is 
one of the largest found in the southeastern States, often attaining a 
length of 3 inches, a width of 54, and a diameter of 2 inches. As a rule 
it is a smoother shell than the ailied species, is less inflated, and has 
not so decided a posterior ridge. 
