In Salt river, rare, small, inch; car- 
dinal tooth almost as in Leptodea , lamellar 
tooth well curved, and fiexuose. 
85 Sp. Unio diaphanus , ( Metaptera ? dia - 
phana 1821. Shell very thin, transparent, 
oval-elliptic, swelled, broader behind, with 
a small wing, surface smooth horny, inside, 
paje incarnate. Length 3-4, diameter and 
axis 3-8 of the breadth. Yar. lineolala with 
fnlvous greenish lines. 
In small streams of Kentucky, one or two 
inches, rare, cardinal tooth compressed, cre- 
mate, lamellar well curved. 
86 Sp. Unio lasmabrachys ( Metaptera ? do. 
1820). Shell rather thick, oval triangular, 
swelled, truncate behind with an arched 
ridge, surface rugose horny, inside bluish 
white, small truncate wing, beaks prominent. 
Length 5-7, diameter 3-7, axis 2-7 of the 
breadth. 
Licking river, &c. 3 or 4 inches, rare, 
deep cavity inside: teeth wide apart, cardi- 
nal crenulate, lamellar very short, broad and 
truncate in the right valve. This and the 
last belong more to Metaptera by the teeth 
than the wings. 
87 Sp. Unio rimosus, ( Eurijnia rimosa. 
1823.) Shell elliptic, thick, thinner, broader, 
and rimose behind: surface olivaceous near- 
ly smooth, inside bluish white. Length 2-3 
diameter 1-6, axis 1-4 of length. 
In the Cumberland river, rare, small 1^ 
inch. Resembling some Amblemas , but evi- 
dently transversal, cardinal tooth crenulate, 
lamellar smooth, short, nearly horizontal, 
but a little curved towards the back. Per- 
% haps a peculiar S. Cf . near to Epioblasma, it 
might be called Lemiox. 
88. Sp. Unio fulvus, \Eurynia fulva . — 
1823.] Shell elliptical, thick before, sloping 
behind, surface depressed nearly smooth, 
bright fulvous or rufous outside and inside. 
Length one half, diameter and axis one fifth 
of the breadth. 
Yar. 2. Fusca,ta } brownish rufous outside, 
pale inside. 
Var. 2. Rufa, quite rufous outside, irides- 
cent inside. 
In Green river, Rockcastle river, &c., — 
rare, fine shell, 2 or 3 inches, cardinal tooth 
crenate, lamellar long and straight. Near 
to my U. auratus. 
G. Obliquaria. 
89 Sp. Unio calendis, ( Obliq . calendis.— 
1821.) Shell thick and swelled, rounded, sub- 
truncate behind, surface with broad flat wrin- 
kles. Length 7-8, diameter 1-2, axis 1-5 of 
the breadth: outside yellowish, inside iride- 
scent and uneven. 
In Dick river, &c. Fine sp. beautiful 
nacre, rare, 2 inches. Near to U. cyclips, 
but smaller, less round, lamellar tooth quite 
oblique, slightly curved as in the Plagiola , 
cardinal tooth striated; probably a Sintoxia. 
90 Sp. Unio Venus , ( Obliquaria Venus. — • 
1820.) Shell oval elliptic, thick and swelled, 
truncate behind with transverse wrinkles, 
outside nearly smooth, of a reddish chesnut 
colour, inside lilac iridescent. Length 3-4, 
diameter 1-2, axis 1-3 of the length. 
In the Kentucky and Cumberland, very 
rare, 3 inches wide; the prettiest of all the 
Unios, resembling a Venus. Lamellar tooth 
thick erose obliqual. My Unio Elliptica sp. 
8, is very near to this: both are of S. G. Ax- 
imedia. 
91 Sp. U nio plateolus , (Obliq ditto. 1823. 
Shell rather thin, broad, elliptic lanceolate, 
attenuate and subacute behind, very com- 
pressed or nearly flat, outside brown nearly 
smooth, inside bluish. Length one half, di- 
ameter and axis 1-5 of breadth. 
At the falls of the Cumberland. Small, 
2 inches, rare. Akin to U. cuprea. Cardi- 
nal tooth small, bilobe, lamellar obliqual, 
short. 
92. Unio teneltus, (Obliq. ditto. 1822.) 
Shell elliptic thin, nearly equilateral, quite 
flat, margin erose, outside minutely striated, 
olivaceous with square green spots, inside 
bluish. Length 4-7, diameter 1-7, axis 3-7 
of the breadth. 
Exceedingly rare, seen only once in a 
stream of the Knob-bills of Kentucky. Size 
one inch. It is an Aximedia which is to be 
a S. G. of Obliquaria . Lamellar tooth 
obliqual very short, cardinal bilobe small as 
in Leptodea. 
93 Sp. Unio bicolor, (Obliq. ditto. 1821.) 
Shell thick elliptic, lanceolate, attenuate and 
subtruncate behind, with an obliquaf ridge, 
outside brown nearly smooth, inside yellow 
above, white beneath. Length 1-2, diameter 
1-3, axis 1-5 of breadth. 
In Kentucky river, 3 or 4 inches, akin to 
U. dilatata , but smoother inside, different 
nacre, axis more anterior: more rare and 
beautiful. Lamellar tooth obliqual thick. — 
The U. dilatata is however also an Obliqua- 
ria and may be called Obi. violacea. 
94 Sp. Uniopallens , (Obliq. ditto, 1821.) 
Shell thick compressed, perfectly elliptic, 
both ends equal, hardly subtruncate behind, 
outside smooth pale yellowish, inside white. 
Length 3-5, diameter 3-10, axis 1-5 of the 
breadth. 
Ohio and Kentucky, rare, 2 or 3 inches. 
Lamellar tooth a little obliqual, short and 
thick, in the left valve furrow closed as in 
the G, Obovaria and Rotundaria. Yet an 
Elliptic which is the same as Ellipsaria. 
95 Sp. Unio rivularis, [Obliq. ditto. 1821] 
Shell rather thick swelled,’ perfectly ellipti- 
cal, slightly arcuate below, outside brown 
and smooth, inside bluish. Length 4-7, di- 
ameter 3-7, axis 2-7 of breadth. 
In the small streams of the Knob hills and 
Cumberland mountains. Very small, hardly 
one inch. Lamellar tooth as in sp, 93. — 
Near to U. sinuata , sp. 67. 
96. Unio fontinalis , (Obliq. ditto , 1S23;) 
Shell thick, rounded, triangular, sub-truncate 
behind; quite rounded before and below; 
outside smooth, yellow, with some green 
spots; inside bluish white. Length 4-5, 
diameter 3-5, axis 2-5 of the breadth. 
At the spring of the source of Green R. 
in the Knobhills, rare, very small, like a Cy- 
das; but belong to S. G Scalenaria , lamel- 
lar tooth obliqual, straight, short. 
