aes SU ae ie le eral 
ENTOMOSTRACA OF MINNESOTA. 229 
KEY TO THE SUB-GENUS CAMPTOCERCUS (VERUS). 
I. Beak pointed. 
A. Head depressed. 
a. Pigment spot larger than theeye.. . . . . . bisSerratus, 229 
b. Pigment spot smallerthantheeye. . . . . . maecrurus, 229 
Be Head directed forward; 2 2.005. ew te ss Peetirestris, 230 
be “Beakrtrmncatepelow.g10 5. 0) seen et wae oe) > latirostris, 230 
III. Beak cleft below or with a forward projection. 
A. Antennules shorter than the beak. . . . . . . Jilljeborgii, 230 
B. Antennules longer than the beak. . . . . . . #£=Yrotundus, 230 
Camptocercus biserratus Schoedler. 
PLATE LXII, Fia. 4. 
Is very nearly related to the next, from which it is distinguished 
chiefly by the fact that the pigment fleck is larger than the eye. 
Schoedler overlooked the fact that in C. macrurus there is a lateral 
line of scales on the abdomen, and relied upon that character to dis- 
tinguish this form. (Schoedler says that the pigment fleck in C. mac- 
rurus is Smaller than the eye, P. E. Mueller says they are nearly equal, 
while in our specimens they are much smaller or nearly equal.) If 
much variability is found, Schoedler’s species seems to rest on a slen- 
der basis. The basal spine of the claw, however, seems to be peculiar 
in sitting on a distinct prominence. 
*Camptocercus macrurus Mueller. 
PLATE LXI, Fias. 10, 10a. 
Lynceus macrurus— Lilljeborg, Schoedler, P. E. Mueller, Kurz, Birge, Herrick. 
This universally distributed species occurs in our larger bodies of 
water and is not rare, though hardly abundant. 
The body is long and nearly rectangular; the head strongly arched 
and keeled. The keel of the head is extended down the whole dorsal 
line. The dorsal line is moderately curved, while the shell is but 
slightly excavated below. The head extends into a blunt beak look- 
ing downward; the direction of the head is somewhat variable (from 
vertical to an angle of about 30 degrees). The eye is much larger 
than the pigment fleck; the antennules are shorter than the beak, and 
have one elongated terminal seta. The post-abdomen is very long 
and has numerous anal teeth as well as a lateral row of scales. The 
basal spine of the claws is large and serrate, the claw itself being 
nearly straight and armed with an increasing series of spines to be- 
yond the middle. The lateral scales of the post-abdomen are incon- 
spicuous. The shell gland is long. The antennules reach to almost 
