290 
THE CABINET OF NATURAL HISTORY, 
In the retired spot where I now reside, I have been 
much amused with a species of Bat which differs in its 
general appearance very much from those which common- 
ly inhabit eastward of the Alleghany Mountains. Just as 
the sun sinks behind the lofty hills which encompass our 
village, it is my custom to pass the twilight hours near an 
old dwelling which stands about midway up one of the highest 
steeps, and is on the road side near the centre of the town. 
Here flocks of Bats commence their nocturnal flights; im- 
mediately on leaving their hiding places, they skim in 
little groups through the air for a few minutes, and then 
gradually separate from each other, some mounting very 
high in the atmosphere, and others descending to the foot 
of the hill for the purpose of drink. These Bats have 
taken possession of the old building, in the space between 
the weather-boards and the inside plastering, and are so nu- 
merous, that I have counted at one time about two hun- 
dred and fifty as they escaped through a single crevice. 
Towards sunset they press forwards to this opening in such 
numbers, that there are often some hard combats between 
them which shall first push through and get on the wing. 
As different genera of insects inhabit the air at greater or 
less altitudes, so those animals which prey upon them will 
fly most generally in different ranges in search of food. 
Our Bat seems to prefer a loftier region for this purpose 
than those which I have noticed in the Atlantic States. By 
this means they also escape in a great measure from their 
deadly foe, the owl, who prowls most successfully in the 
regions below. The following is a description of one of 
these Bats, which darted into my study the other evening. 
Y espertilio Domesticus. — Green. 
Four incisors in the upper jaw near the canines, with a 
large unoccupied space between them, each pair being of 
unequal lengths — the tooth nearest the canines the long- 
est; upperlip furnished with numerous short bristles; nares 
placed laterally at the base of a wart-like prominence, 
which gives to the nose a slightly bifid appearance; ears 
remote, naked, broad, entire, much longer than the head; 
auriculum, or tragus, entire, lanceolate, obtuse rather 
more than half the length of the ears; pelage above mouse 
colour, darkest over the nose; lighter below, with a dark 
fawn coloured spot near the axilla; wings and interfe- 
moral membrane naked; tail scarcely projecting beyond 
the membrane; length from the tip of the nose to the end 
of the tail, three inches and one-fourth; breadth across the 
wings, when fully expanded, nine inches and a quarter. 
Shells. 
The stream of water which flows during the summer 
and autumnal months sluggish along the base of our hills, 
becomes in the spring a deep and rapid river from the 
melting snows and heavy rains. Large boats and rafts of 
timber are thus easily floated from the village to Pitts- 
burg. At the season of the year when I visit this spot, 
the creek, as it is called, contains but very few fish, but it 
abounds with many interesting aquatic productions. Seve- 
ral species of the Unio and Cyclas in many places literally 
pave the bed of the stream. Near its mouth most of the 
fresh water shells common to upper portions of the Ohio 
river are found in great perfection and abundance. Higher 
up the stream we find beautiful specimens of the Unio 
Rubiginosus in considerable numbers, a species not com- 
monly met with near the junction of the creek with the 
Ohio river. Every American conchologist is aware that 
our great western rivers and their tributary streams con- 
tain an almost infinite variety of species belonging to the 
genus Unio. Some of the species appear to inhabit all 
portions of these waters indiscriminately, while others 
seem to be confined to distinct and often remote localities. 
In illustration of these remarks, I would now describe a 
few large shells which I examined and named a number 
of years since, but which seems to have escaped the notice 
of our conchologists. The first specimens of this shell which 
I observed were from the Falls of St. Anthony; I after- 
wards received it from the Bayou Teche, but I have never 
discovered nor ascertained that it exists in the Ohio. 
Unio Capax. — Green. 
Testa ovato-triangulari, ventricosa ; valvulis tenuibus-hiantibus ; 
natibus prominentibus ; margarita cceruleo-alba et iridescente. 
The valves of this shell are much more convex or 
globose than any of the uniones which I have seen; and as 
they are quite thin compared with most of the western 
species, the cavity in which the animal is lodged is ex- 
ceedingly capacious — hence its name. The anterior end 
is broad, rounded, and slightly angular near the hinge; the 
posterior margin is very narrow, and also rounded; these 
valves do not close perfectly on each other, but gape at 
the opposite margins; this is more remarkable in old than 
in young individuals. The epidermis is smooth, yellow- 
ish, and frequently clouded with brown. The nacre is 
bluish white, and often very beautifully iridescent. The 
beaks are recurved over the tegument. The teeth resem- 
ble very much those of the U. ovatus of Mr. Say, but 
they are much thinner. These characters, I think, will 
be sufficient to distinguish the Unio Capax from every 
other shell. 
On some other occasion I propose to notice more parti- 
cularly the multitude of land shells which inhabit our 
