Cyclops. 



205 



total length. Antennae 17-jointed, shorter than first cephalo- 

 thoracic segment. Abdomen slender, the last segment armed 

 on its posterior border with a row of small spines. Furca 

 slender, longer than the last two abdominal segments, lateral 

 spine at two-thirds the distance from base to extremity. Of 

 the terminal setae, the outer is a short blunt spine, the inner 

 slender and somewhat longer; the outer median seta rather 

 more than two-thirds the length of the inner. 



The armature of the terminal joints of the swimming feet is 

 as follows : 



FIRST FOOT. 



Outer br. ex. 3 spines. Inner br. ex. 1 seta. 



ap. 2 setae. 

 in. 2 setae. 



ap. 1 spine, 1 seta, 

 in. 3 setae. 



SECOND FOOT. 



Outer br. ex. 3 spines. Inner br. ex. 1 seta. 



ap. 1 spine, 1 seta. ap. 1 spine, 1 seta, 



in. 3 setae. in. -^3 setae. 



THIRD FOOT. 



Outer br. ex. 3 spines. Inner br. ex. 1 spine, 



ap. 1 spine, 1 seta. ap. 2 spines, 



in. 3 setae. in. 3 setae. 



FOURTH FOOT. 



Outer br. ex. 3 spines. 



ap. 1 spine, 1 seta, 

 in. 3 setae. 



Inner br. ex. 1 spine. 

 ap. 2 spines, 

 in. 2 setae. 



The fifth foot is two-jointed. The basal joint is very broad 

 and is armed with one seta. The terminal joint is armed with 

 one seta and a short spine. 

 , Length about 1 mm. 



Herrick's* description of C. brevispinosus is so imperfect 

 that it is difficult to identify the species with certainty. The 

 armature of the swimming feet is different from that in C. par- 

 cus, although one might infer from his statement that it is the 

 same. The form and armature of the furca, however, is char- 

 16— A. & L. 



