552 -Storer on the 
height to its length, as 2 to 8. The distance be- 
tween the dorsals, is equal to half the length of the 
first dorsal. 
The second Dorsal is considerably higher than the 
first; before reaching the caudal fin, to which it is 
continued, it is depressed. 
The Caudal fin is a simple membrane, triangular 
at its termination, and uniting with the anal fin, 
which is very small. Anus small. 
Le Sueur dwells upon the “white dorsal fins d 
his specimen was six inches long. My three speci- 
mens, one, five inches, a second, six inches in length; 
have both dorsals perfectly white ; in the specimen 
just described, seven inches long, the margin of the 
second dorsal is of the same color as the back of the 
fish. 
Ls 
AwwocokeTEs. Dumer. 
P Generic characters. Form of the body, the bran- 
chial apertures and fins, like those of the Lam- 
preys; upper lip semi-circular, with a straight, 
transverse under lip ; mouth without teeth, but fur- 
nished with numerous short membranous cirrhi. 
A. bicolor. The Mud Lamprey. 
Trans, of Amer. Phil. Soc. new series, vol. i. p. 386. 
I have never been able to procure this species, and 
therefore extract Le Sueur’s description, drawn up 
from a specimen sent him from Northampton, by Dr. 
Hunt, which was taken in the Connecticut river : 
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