420 NOTES ON FLORIDA UNIONID:—SIMPSON. 
character is constant in all the specimens I have seen of this very varia. 
ble species. I have before me six shells sent by Mr. B. H. Wright to 
the Museum (Museum No. 91133) from Lake Ashby, labeled by him U. 
Fryanus, that agree essentially with his figure and description of that 
species, which I am sure are only a variety of coruscus. They are 
larger than Lea’s specimen, somewhat less inflated, and not quite so 
solid. Yet in general outline, color of epidermis, nacre, and teeth 
there is no essential difference, and they have the remarkable trunca- 
tion of which I have spoken. Mr. Wright sent nine unios to the Mu- 
seum (Museum No. 91135) from Lake Dias, which he labeled Unio 
diasia, five of which are no doubt U. tetricus and the remainder a form 
of coruscus with a dark epidermis. He also sent five shells, which he 
labeled Unio Waltoni, from Lake Ashby (Museum No, 91132), which 
are not that species, but a form of coruscus slightly drawn out at the 
posterior end and having a rough epidermis. Another shell is before 
me collected by Dr. Stimpson, and labeled by him “ Unio tetricus Lea, 
Tampa Bay” (Museum No. 73182), which is very much like the last, 
but is rather narrower across the anterior end, and is no doubt the 
species under consideration. Specimens in Mrs. Andrews’ collection, 
which Mr. Wright labeled ‘“ Unio coruscus Gld.,” are almost exactly 
like those he has called U. Waltoni, to which I have referred. 
I have no less than fifteen different lots of unios before me, sent under 
various names, collected in numerous localities from the St. Johns to 
Tampa, which I am satisfied are all forms of the present species, as I 
find no characters among them on which to base a separation. 
Unio occultus Lea. 
(Plate Lxu, Figs. 5, 6.) 
Unio occultus Lea. Obs. Iv, p.37, Pl. xut, Fig. 7, August 18, 1843. Black Creek and 
Lake Monroe; S. B. Buckley. 
This species approaches very close to some specimens of tetricus, but 
is usually larger, not so wide, is not so much disposed to be biangulate 
behind, and is rather more lenticular than that shell. Some of the 
young are very close to young fuscatus, but are hardly so wide and, as 
far as I have seen, are darker and solider. Itis hard to separate, when 
young, from half-grown specimens of denigratus, but the latter is in gen- 
eral more rhomboid in form. The epidermis is usually rather dark and 
feebly rayed, the nacre bronzy or coppery, and not very bright. 
Unio fuscatus Lea. 
(Plate Lx111, Figs. 2, 4.) 
Unio fuscatus Lea. Obs. Iv, p. 31, Pl. xt, Fig. 4, August 18, 1843. Black Creek; S. 
B. Buckley. 
Much confusion exists concerning this species as well as the preced- 
ing and following. Certain forms of tetricus approach very close to the 
