EN'TOMOSTRACA OF MINNESOTA. . 95 
*Cyclops brevispinosus Herrick. 1884. 
PLATES XXIII, Fias. 1-4; XXIV, Fies. 7-12. 
This species may be regarded as the pelagic representative of 
C. parcus. In the original description the following differences were 
noted. The form is more slender and the stylets are greatly elongated, 
the outer caudal seta is reduced to a short ciliate spine, and the fourth 
foot is differently armed and the receptaculum is somewhat different 
in form. 
Marsh says that one might infer from my statement that the arma- 
ture of the swimming feet is the same as in C. parcus, but how this 
could be possible in the face of the plain statement of difference and 
figure of the fourth foot it is hard to see. 
The first segment of the compact thorax is half its entire length 
and the antennz are rather shorter. The abdomen is rather slender 
and tapering. The stylets are 4.5 times as long as wide, and the 
small lateral seta is more than two-thirds its length from the base. 
The outer terminal seta is transformed into a very short stout serrate 
spine, shorter than the inner seta and one-third as long as the stylets. 
The outer median seta is less than three times as long as the stylet and 
is naked for more than half its length, when it is suddenly narrowed 
and very closely pectinate to the end. The inner median seta is 
almost exactly three times as long as the stylet, and is sparsely pecti- 
nate for its middle third and closely so for its apical third. 
The armature of the feet is as follows: 
First Foor. 
ex. 3 spines. ex. 1 seta. 
Outer ramus | 2 sete. Inner ramus; ap. 1 spine, 1 seta. 
in. 2 sete. in. 3 sete. 
SECOND Foor. 
ex. 3 spines. ex. 1 seta. 
Outer ramus {8 1 spine, 1 seta. Inner ramus {8 1 spine, 1 seta. 
in. 3 sete. in. 3 sete. 
THIRD Foot. 
ex. 3 spines. ex. 1 spine. 
Outer ramus ; ap. 1 spine, 1 seta. Inner ramus; ap. 2 spines. 
in. 3 sete. in. 3 sete. 
FouRTH Foot. 
ex. 3 spines. ex. 1 spine. 
Outer ramus { ap. 1 spine, 1 seta. Inner ramus; ap. 2 spines. 
in. 3 sete. in. 2 sete. 
The basal segment of the fifth foot is little expanded and bears one 
seta while the short second joint has an apical seta and a small lateral 
extemal epine.< hormula, torvantennee, 2... Ce ee 
Antennules rather short. Length 1.0mm. Marsh suggests that this 
may be a pelagic form of (. viridis var. Americanus, in which case 
C. parcus would become a variety of the same species. 
