16 DESCRIPTION OF 
Hab. Roanoke River, Lafayette, and near Shenandoah Spring Brook. J. A. Warder, M.D. My 
Cabinet, and Cabinets of Dr, Warder and T. G. Lea, Cincinnati. Diam. .38, Length .56 of an inch. 
Remarks.—Three specimens are before me, all of which differ more or less. Two of 
them are rather acutely carinate, with a dark epidermis and three rather large bands, the 
other is of a rather light horn colour with indistinct bands in the interior, and having no 
carina on the lower whorl. On the columella, there is a slight swelling. The aperture 
is about one-half the length of the shell. 
AMNICOLA. . (Gouzp.) 
The genus Amnicola, proposed by Dr. Gould, and adopted by Mr. Haldeman, in his 
table of “‘ Water-breathing Lymniades,” is separated from the genus Paludina; Paludina 
lustrica, (Say,) being made the type. There seems to be sufficient reason for this divi- 
sion, as the animal is different, and the operculum subspiral, differing in this respect en- 
tirely from that of Paludina, which is concentric. 
It is difficult in the present state of our knowledge of these small shells to say how many 
species are known, as the animals and opercula of all the small species of Paludina have 
not yet been observed. P. imosa (Say,) and porata (Say,) will belong to this genus.* 
AMNICOLA ORBICULATA. 
Testa orbiculaté, subtenui, luteold, levi, umbilicatd; spird brevi; suturis valde impressis; anfractibus quinis, infla~ 
tis; aperturd magna, rotundd. 
Shell orbicular, rather thin, yellowish, smooth, umbilicate; spire short; sutures much impressed; whorls five, inflated; 
aperture large, round. 
Hab. Springfield, Ohio. T.G. Lea. Schuylkill? near Philadelphia. My Cabinet, and Cabinet of 
T. G. Lea. Diam. .18, Length .18 of an inch. 
Remarks.—This species is very closely allied to Am. parva, and may perhaps prove to 
be only a variety of it. ‘The specimens before me are all larger, and they appear to be 
more globose. ‘The aperture is about one-half the length of the shell. I found a single 
specimen of this species among many small shells which were thrown together in a box, 
as being collected from our vicinity. It may be possible that it is an Ohio specimen 
gotten by accident into the box.+ 
AMNICOLA PARVA., 
Testa obtuso-conicd, subtenut, luteold, levi, umbilicatd; spird brevi; suturis impressis; anfractibus quaternis, infla- 
tis; apertura magné subrotundd. 
Shell obtusely conical, rather thin, yellowish, smooth, umbilicate; spire short; sutures impressed; whorls four, inflated; 
aperture large, nearly round. 
Hab. Springfield, Ohio. T. G. Lea. My Cabinet, and Cabinet of T. G. Lea. Diam, .15, Length 
.18 of an inch, 
Remarks.—The shell described by Mr. Anthony as Paludina Cincinnatiensis, resem- 
bles this species, but it is more elevated in the spire, and is a larger shell. It is more 
* The shell described by me in vol. 6, page 22, of the Transactions, as Paludina pallida, and previously by Mr. Say 
as Melania isogona, but which I had not before seen, has been carefully examined by my brother T. G. Lea of Cincinnati, 
as to the form and habits of the animal. There can no longer be any doubt of its belonging to the genus Amnicola; it 
should therefore be called Amnicola isogona. 
+ Since the above was written, I have observed a single specimen of this shell among those in the Academy of Na- 
tural Sciences, with the true porata, from Cayuga Lake. It is, therefore, probable that it exists in our rivers flowing 
into the Atlantic. 
