BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 11. N:o 15. 39 
Colour. Above dark-fuscous, spotted and mottled with 
yellowish. 
Length. 8—13 mm. 
Hab. Lake Superior, and lake Huron. North America. 
a. Mancasellus tenax "var. dilata. O. HARGER. 
Syn. 1874. Aesellopsis tenax 
"rar. dilata. O. HARGER. S. I. SMITH. >»The Crusta- 
cea of the fresh wa- 
ters of the United 
States». Report of the 
U. S. Commissioner of 
Fish and Fisheries. 
Part 2, p. 661. 
It differs from the species in: the flagellum of the first 
pair of antenn&e containing one or two joints more; the 
lateral portions of the head and segments of the body are” 
expanded so that the outline of the animal is a broader oval. 
The sinus in the lateral margins of the head are narrow 
incisions, rounded at the bottom, but with the sides some- 
times meeting. The metacarpus of the first pair of pereio- 
poda is nearly as much enlarged, in the males, as in Åsellus 
communis, SAY, and is armed on the anterior margin with 
three acute teeth, of which the middle one is the largest. 
Hab. Detroit River, Michigan, North America. 
2. Mancasellus brachyurus. OO. HARGER. 
Syn. 1876. Mancasellus brachyurus. O. HARGER. »Description of Manc- 
asellus brachyurus, a 
new fresh water Iso- 
pod. The American 
Journal of Science and 
Arts. Third Series. Vol. 
11, p. 304. 
The lateral margins of the head are entire. The meta- 
carpus of the first pair of pereiopoda is armed with a pro- 
minent acute tooth on the anterior margin, near the base (in 
