2 
elucidate and isolate the species. All the 
great naturalists know and do this. 
The works wherein their erroneous labors 
are found cost above $100! (mine only 50 
cents.) This has put it out of my power, 
as yet, to verify all their mistaken and sy- 
nonymous names. A , complete synonymy of 
these shells will soon be required, which I 
may perhaps undertake in future, unless it 
is done by Mr. Poulson, who has translated 
and means to publish my Monograph of 
1820. This continuation will be a supple- 
ment to his translation. I mean to give in 
it my shells under my own names, imposed 
as soon as found in 1821 and 1822 chiefly, 
the undoubted right of a previous discoverer 
and explorer. If some of them are already 
well named and described, let their names 
be compared and the oldest or best prevail, 
as those of my old Monograph ought in all 
cases. C. S. R. Philadelphia , Oct. 1831. 
I. TRIBE— UNIQ. 
1. N. G. Efioblasma. Differs from 
Amblema and Ellipsaria by lamellar tooth 
obliqual, divergent towards the back and 
straight. Axis nearly terminal. The Unio 
or Jlmblema torulosa . Sp. 55 perhaps belongs 
here also. 
76 Sp. Unio hiloba , or Epioblasma biloba , 
discovered 1821. 
Elliptical, both ends rounded, back convex, 
belly bilobed, sides rugose, more or less gib- 
hose, swelled before, greenish brown outside, 
bluish white inside. Breadth 2-3, diameter 
2-5 of the length. 
Var. 1. Pallida , not greenish, rufescent, a 
little longer. 
In Green river and Kentucky river, about 
3 inches long. Remarkable species, very 
rare, summits prominent, teeth striated, the 
lamellar short, reaching only to the middle. 
2. N. G. Toxolasma, Differs from Amble- 
ma, Plagiola and Sintoxia , by lamellar tooth 
not obliqual but arched parallel with the 
back, axis nearly terminal, general form 
rounded, back curved. 
77 Sp. Unio cyclips. {Toxolasma cyclips.-r— 
18 20.) Shell thick, rounded-elliptical, swell- 
led subglobose, subrugose and yellowish out- 
side, incarnate inside. Breadth 6-7, diam- 
eter 4-8 of the length. Axis l-10th. 
Var. I. Fuscata. Larger, brown outside, 
and nearly smooth, whiter inside, longer la- 
mellar tooth. 
Var. II. Lutescens. Yellow outside, blu- 
ish white inside. 
River Ohio and Mississippi 2 to 4 inches, 
beautiful nacre, lamellar tooth carinate, 
serrulate as in many other species. It is said 
that this is the U. abruptus of Say. I can- 
not see any thing abrupt in it; my name 
means Round Ellipsis. 
78 sp. Unio cinerescens {Toxolasma ditto. 
1820.) Shell thick rounded oboval, a slight 
posterior obliqual ridge, nearly smooth and 
cinerescent brown outside, bluish while in- 
side. Breadth S-9, diameter 6-9 of the 
length. Axis 1 -9 th. 
River Ohio and Kentucky. About 2 inch- 
es, cardinal tooth much striated, lamellar not 
serrulate. 
79 sp. Unio lividus , (Toxolasma do. 1822.) 
Shell elliptical swelled not thick, outside sub- 
rugose, brown, inside livid purplish. Length 
3-4, diameter 3-8, axis 1-4 of the breadth. 
In Rockcastle river, exceedingly rare.™ 
Size only one inch, lamellar tooth long, thin 
curved, not serrulate. 
80. Sp. Unio jlexus. [Toxolasma, ditto, 
1821. ] Shell thick rounded, swelled, undulate 
below; outside subrugose, olive brovvn, in- 
side bluish white. Length 5-6, diameter 1-2, 
axis l -6th of the breadth. 
In the Kentucky river, rare, 1 or 2 inches, 
lamellar tooth well curved, thick; not ser- 
rulate. 
3. N. G. Bariosta. Form of Scalenaria , 
lamellar tooth curved, and not obliqual, as 
in Sintoxia , shell transversal, triangular. 
81. Sp. Unio ponder osus. {Bariosta ditto, 
1820.) shell very thick and heavy, oval trian- 
gular, rounded before, curved slope behind, 
with an oblique ridge ending to a point, a si- 
nus next to it: outside rough and blackish; 
inside incarnate, iridescent, uneven. Length 
3-5, diameter 2-5, axis 1-4 of the breadth. 
In the lower Ohio and Mississippi. Fine 
shell, with beautiful nacre, 3 to 5 inches 
broad; cardinal tooth striate, lamellar tooth 
scabrous! Many uneven wrinkles inside. 
The U. sinuata Sp. 67, belongs to this sec- 
tion Bariosta having a similar lamellar tooth: 
but it is broader, more elliptical, without 
ridge, and white inside; the sinus is also 
more central. 
82 sp. Unio vittatus ( Lampsilis ? vittata — 
1818.) Shell oval, swelled, rather thin, 
broad subalate and subtruncate behind with 
two or three oblique ribs longitudinal, round- 
ed and rugose before, sides smooth, outside 
olivaceous, radiated with narrow straight 
greenish rays, bluish white inside. Length 
3-4, diameter one half, axis one third of 
breadth. 
In Green river, 3 inches broad or more. 
Very near my Lampsilis fasbiola, sp. 26: — 
but it is larger, rounder, with straight rays. 
Cardinal tooth crenulate, lamellar tooth not 
flexuose, but well curved in the right valve; 
short, compressed, truncate behind. 
83 Sp. Unio inontanus , {Eurynia mon - 
tana, 1823.) Shell thin, elliptical, compres- 
sed, behind broad a little winged, end trun- 
cate, outside nearly smooth brown, a little 
laminated and fulvous around, inside bluish. 
Length one half, diameter and axis 2-5 of 
breadth. 
In the streams of the Alleghany and Cum- 
berland mountains. About 2 inches. La- 
mellar tooth very long, nearly straight, a 
sinus above it. 
S4 Sp. Unio diploderma , {Lampsilis ditto . 
1822. ) Shell thin elliptical, hardly swelled: 
back hardly bioader: surface a little ribbed 
with a double epidermis, the outer rufous, 
the inner greenish: inside bluish purple. — - 
Length 7-12, diameter 1-3, axis 1-4 of 
breadth. 
