416 NOTES ON FLORIDA UNIONIDA—SIMPSON. 
cardinal teeth are rather compressed, the laterals straight, and sud- 
denly truncated at the posterior end; the nacre varies from silvery 
white to salmon red, and when colored shows through the epidermis, 
and is often beautifully iridescent. One of Lea’s specimens measures 
nearly 3 inches in width by 13 in length. A magnificent specimen is 
before me from the cabinet of Mrs. Andrews, collected by I. Rugel, 
and by him labeled “ U. radians, Lea, Othealooga River, Florida,” which 
nearly equals Lea’s largest specimen in dimensions, and is elegantly 
and distinetly rayed. 
GROUP OF UNIO NASHVILLENSIS. 
A widespread group represented by many species, ranging from 
North Carolina to Iowa, and south to Texas and Florida. The species 
vary from oblong to wide, are usually rather thin in structure, the pos- 
terior end is generally pointed, and more or less angulated in outline, 
and the posterior ventral region 1s always well developed in the females, 
sometimes greatly so. The general outline of the shells is much like 
that of the luteolus group, but they are smaller, less solid, and often 
have dark nacre, varying from lurid reddish to deep purple. With few 
exceptions the epidermis is rayed. 
Unio concestator Lea. 
(Plate Lv, Figs. 2, 3, 4.) 
Unio concestator Lea, Obs. VI, p. 66, Pl. x11, Fig. 48, Feb. 17, 1857. Creeks near Col. 
umbus, Ga.; Bishop Elliott. 
I have only seen a single specimen of this species from Florida, which 
belongs to the Rev. A. Dean, of Muncy, Pa., and was collected in Lake 
Harris by Mr. Wright. It is a female, strongly developed in the pos- 
terior ventral region, with silvery iridescent nacre, and dark ash-colored 
epidermis varying to yellowish and greenish and slightly rayed. It 
does not agree in color with any specimen of concestator I have seen, 
but does in general form, and is probably an extreme variety. Atany 
rate I do not care to found a species on a single specimen possessing no 
stronger distinctions than mere color markings. It is not very differ- 
ent from some of the specimens I have seen of nashvillensis, but the 
distribution of concestator is southeastern, while the former is found in 
the central Southern States. It is probable that a number of the 
species of this group, such as fallax, nashvillensis, lienosus, and the 
one under consideration, as well as some others, are merely varying 
forms of one and the same thing. 
Unio tenerus Rav. 
(Plate Lyi, Figs. 5, 8.) 
Unio tenerus Rav., Ravenel’s catalogue, p. 
, 1834. 
Several specimens of this species are in the collection of Mrs. George 
Andrews, labeled “Florida,” without locality. It is close to nash- 
