I 0 ee ae ee oe 
: Es 
oe . ENTOMOSTRACA OF MINNESOTA. 119 
ments of a rather small specimen: First segment of cephalothorax 
0.24, second segment 0.068, third segment 0.06, fourth segment 0.036 
mm.; the remainder of the body to the stylets measures 0.24 mm., 
while the stylets themselves are 0.024 mm. long and bear a lateral 
Spine about one-third their length from the apex. The longest seta is 
0.24 mm. long, the outer median seta being about 0.19 mm. The body 
is comparatively rather slender and tapering, with an unusually long 
first thoracic segment. (Measurements of a large specimen of this 
Species may serve to indicate the observed fluctuation in size: Length 
0.81 mm., thorax 0.50, abdomen 0.31, stylets 0.06, longest seta 0.40, 
outer median seta 0.36 mm.) The antenne are considerably shorter 
than the first thoracic segment, being about 0.19 mm. long, the sev- 
enth and eighth joints about equal and the longest of the eleven seg- 
ments. The first joint is very large. The antenne in a state of rest 
assume a curved position. The antennules are small, the terminal 
segment measuring (in the animal first above referred to) 0.032 mm. 
The labrum has six similar teeth, which are bordered on either side 
by a larger one. The longest joint of the outer maxilliped measures 
0.06mm. All the feet are usually two-jointed in both rami. The 
outer ramus of the first pair of feet has the terminal joint armed exter- 
nally with three stout spines, terminally with two sete, and internally 
with three setze. The second and third pairs of feet are alike in their 
Spinous armature, the outer side of the terminal segment bearing 
three spines, the end a very large toothed spine and a seta, and the 
inside four sete. The fourth foot has two spines on the outside of the 
terminal joint, a heavy spine and a seta terminally, and four set 
within, while the terminal joint of the inner ramus bears externally 
one spine, apically two spines, and internally three sete. The fifth 
foot consists of a fleshy basal segment, more or less coalescent with 
the last thoracic segment and bearing a curved spine externally, and 
a terete terminal segment 0.012 mm. long, which has an apical seta 
four times its own length. The abdomen is slender and its last seg- 
ment bears a series of spines dorsally on the caudal margin. The egg- 
sacs are appressed and contain eight to twenty rather large ova. The 
color is bronzy and opaque. 
Although Marsh says his ‘‘specimens agree very well with the 
descriptions of Sars and Schmeil, the only marked difference being in 
the length of the caudal sete,’’ we find several points of divergence 
which may make it necessary to create a new variety or species. The 
stylets are much shorter in the American form and the sete are 
longer. The external apical seta is a well-formed spine. The form of 
the basal segment of the fifth foot is more as in C. varicans, there being 
a decided protuberance to receive the second joint. The receptacu 
