72 RAFINESQUE’S 
I. TRIBE.—UNIO. 
1. N. G. EpioptasmMa. Differs from Amblema and Ellipsaria by 
lamellar tooth obliqual, divergent towards the back and straight. 
Axis nearly terminal. The Unio or Amblema torulosa. Sp. 59d, 
perhaps belongs here also. 
76. Sp. Unio biloba or Epioblasma biloba, discovered 1821. 
Elliptical, both ends rounded, back convex, belly bilobed, sides 
rugose, more or less gibbose, 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 incheslong. Remark- 
able species, very rare, summits prominent, teeth striated, the lamel- 
lar short, reaching only to the middle. 
2. N. G. Toxorasma, Differs from Amblema, Plagiola and Sin- 
toxia, 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.—1820.) Shell thick 
rounded-elliptical, swelled subglobose, subrugose and yellowish out- 
side, incarnate inside. Breadth 6-7, diameter 4-8 of the length. 
Axis 1-10th. 
Var. I. Fuscata. Larger, brown outside, and nearly smooth, 
whiter inside, longer lamellar tooth. 
Var. II. Lutescens. Yellow outside, bluish 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 cannot see any thing abrupt init ; 
my name means Round Ellipsis. 
T8sp. Unio cinerescens ( Toxolasma dilto.—1829.) Shell thick, 
rounded oboval, a slight posterior obliqual ridge, nearly smooth and 
cinerescent brown outside, bluish white inside. Breadth 8-9, diameter. 
5-9 of the length. Axis 1-9th. 
River Ohio and Kentucky. About 2 inches, cardinal tooth much 
striated, lamellar not serrulate. 
79 sp. Unio lividus, (Toxolasma do. 1822.) Shell elliptical 
swelled not thick, outside subrugose, 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, lamel- 
lar tooth long, thin curved, not serrulate. ; 
