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Fishes of Massachusetts. 549 
the mouth; seven apertures on each side of the neck, 
leading to seven branchial cells; no pectoral or 
ventral fins; the skin towards the tail extending 
in a fold from the body both above and below, 
forms dorsal, anal, and caudal fins. 
P. Americanus. Le Sueur. The American 
Lamprey. 
Trans. of Amer. Phil. Soc. new series, vol. i. p. 382. 
This species, which is far from being common in 
our Bay, is taken in deep water, attached to pieces 
of drift wood, and the bottoms of boats and vessels. 
In its spawning season, it ascends the numerous 
rivers. It is taken in large quantities in the Merri- 
mack river, at Lowell. Dr. Elisha Bartlett writes 
me, that “they ascend the rivers a little earlier than 
the shad, and move mostly in the night. It is not 
known, by the fishermen, when they return, as they 
are never seen. There is a notion that they all die. 
They are often seen. in the summer, in pairs, at 
work together, constructing a little mound of stones. 
They build this about three feet in diameter at the 
base, and about two feet high, of stones from the 
size of an ounce bullet to that of the fist. They 
often aid each other in carrying the same stone. 
This is pretty evidently a labor of love, as they 
copulate once in five minutes, or so, during the 
whole time. The young go down the river, when 
the water begins to freeze. They are then from . 
six to eight inches long.” 
It occasionally attains the weight of four pounds. 
