THE - CONCHOLOGISTS’ - EXCHANGE. 
elliptical, perforate, columella thickened and 
reflected over the perforation. I found this 
shell in 1879, quite plenty in a slough in Green 
Township, in this county, crawling over flat 
slabs of coal measure limestone, a short dis- 
tance below Blaine’s coal shaft. At the time 
I supposed them to be Amnicolas and only 
secured about forty specimens. I have looked 
the same locality over many times since and 
have failed to be rewarded with a single speci- 
men. This should prove a warning to shell 
collectors. When you have an opportunity to 
secure a shell do not defer it until a more con- | 
venient season, for very likely it will never 
come. 
Genus Physa. Draparnaud. 
94.—Physa gyrina, Say. 
Shell heterostrophic, oblong, rather solid, 
whirls from five to six, gradually acuminating 
to an acute apex, sutures slightly impressed, 
labrum slightly thickened, spire elongated. 
This very common and well-known species is 
known to inhabit a very wide area of country, 
having a distribution from Vermont to Utah, 
also found in most of the Southern States. It 
‘is our most common species, being found in all 
the sloughs and lakes of the Mississippi River 
bottom ; along all the creeks that flow through 
our county above the river bluffs, and also in 
our small ponds and basins, in many places 
associated with Physa heterostropha. It va- 
ries considerably in color, size and texture, be- 
ing much lighter in color and much more solid 
in the river bottom than it is above the bluffs. 
This species is very active both in walking and 
gliding along on the surface of the waters, 
shell downward. This very remarkable species 
puts in an appearence very early inthe Spring, 
and can endure a considerable degree of cold 
In the month of April I have watched its mo- 
tions through the ice, sufficiently thick to bear 
up a man, and have seen it in vast numbers 
crawling around on the bottom of shallow 
‘ponds. Full of motion and life it remains 
with us much later in the season than Limnzea 
as I have found fine specimens in October. 
95:—Physa heterostropha, Say. 
Shell sinistral, subovate, color pale yellow, 
chestnut brown to reddish wine color; whirls 
five, body whirl large, the others small, termin- 
ating abruptly to an acute apex; aperture large, 
oval, within pearly, often blackish ; lip thicken- 
ed, sometimes tinged with red. ‘This species 
has even a much greater distribution than 
gyrina, being found in the British possessions, all 
over the United States, and even in Mexico. 
Here it is much less common than eyr7za, 
rarely found above the Mississippi River 
bluffs. It is, however, found in all the lakes 
and sloughs of the river bottom, often associ- 
ated with gy7z7za. Both the gyrina and heteros- 
tropha as found here are very variable, yet it is 
by no means likely that those variable forms 
are more than varieties of those two protean 
species. 
Genus Planorbis. Guettard. 
SUB-GENUS HELISOMA, SWAINSON. 
96.— Planorbis (felisoma) trivolvis, Say. 
Shell, pale yellow to light horn color, often 
chestnut brown, sub-carinate above and be- 
neath, whirls three to four, striate across, with 
fine raised equidistant, acute lines, forming 
grooves between them, spire concave, aperture 
large, lip a little thickened internally, and of a 
red or brownish color; vaulted above, umbili- 
cus large, exhibiting the volutions. ‘This spe- 
cies probably inhabits all North America, as far 
south as Mexico, and of course throughout this 
vast extent of country presents many vyaria- 
ations. ‘The typical form is not very common 
in our county, but seems to be found rather 
sparingly in all stations where there is water. 
To be Continued. 
NOTES ON THE UNIONIDA OF 
FLORIDA. 
BY DR. S. HART WRIGHT & BERLIN H, WRIGHT. 
Unio granulatus, Lea, Sig., little grains, 
R=—=5 0} 
Shell thin, about an inch long. and resembles 
U. parvus, Bar. On the beaks, and about 4% 
inch out, there are several concentric undula- 
tions or granules, giving the appearance of 
folds. Epidermis dark olive, generally rayless 
and generally sulcate in front. Found in 
Manatee River, on the west coast of Florida, 
by Mr. C. T. Simpson. An Alabama shell. 
