1894.] Notes on a Species of Simocephalus. 395 
NOTES ON A SPECIES OF SIMOCEPHALUS. 
F. L. Harvey, Orono, Me. 
In a gathering from a spring swamp near Orono, Me., brought 
into the laboratory by Mr. O. W. Knight, one of my pupils, was 
found a fresh water crustacean in great abundance. The spe- 
cies is near ©. vetulus Mueller, but as it differs in several 
points from the descriptions and figures of that species given 
by Herrick in his Minnesota’ Reports, the following observa- 
tions, accompanied by drawings, are made regarding it. 
The strie in our specimens arise on the ventral margin 
from triangular or quadrangular spaces instead of hexagonal as 
stated by Herrick. See Fig. 4. These strie are often anas- 
tomosing and lost in the dorsal region in fine reticulations. 
The prominence on the posterior part of the shell is variable ; 
obtuse, or obtuse-angled and occasionally obsolete, and also 
variable in position. It is usually near the dorsal region but 
in one specimen it is located in the middle. Itis always armed 
with blunt teeth, which extend above and below along the 
posterior margin of the shell. See Fig. 1. Head often concave 
in front, though in some specimens rounded as shown in Her- 
Tick’s figures. Eyes placed near the end of the beak, 
round, bordered with circular clear cells and bearing on 
the front, six or seven circular facets darker than the general 
ground color. What is called the eye seems to be an eye spot 
bearing dark colored ocelli, reminding one of the eye spot of a 
Thysanuran. See Fig. 5. 
Inferior antenne fusiform, bearing in front a prominence 
armed with a stout spine, which is ‘bulbous at the base and 
90x. long. The body of the antenne encircled by about six 
rows of minute blunt teeth, one row of which adorns the dis- 
tal margin. From the end arise two series of four slender 
Sete, bearing small bublets at the end. See Fig. 6. 
Superior antennæ large. There are three short joints at 
the base which give great freedom of motion between the 
