COPEPODA 



777 



87 (88) Setae of fifth feet very elongate, last antennal segment armed with 

 serrate hyaline plate; common. 



Cyclops leuckarti Claus 1^857. 



This species is easily recognized from tlie form 

 of the furcae. No other species with seventeen 

 segmented antennae has this characteristic form 

 of short rami, with the lateral setae placed at 

 about midway of its length. If one can make out 

 the structure of the fifth feet (Fig. 1221), he can 

 be quite sure of the identification; for no other 

 American species has this form, with the excep- 

 tion of tenuis, and, so far, tenuis has been found in 

 only one locality. This species, as has been noted 

 in another place, is peculiarly interesting; for it 

 is almost world-wide in its distribution, having 

 been found in all continents. Moreover, the Uttle 

 variations which are found in details of structure 

 are also world-wide, so that change of location 

 leuckarti. A, abdomen seems to have no effect on the species. 

 B, fifth foot of same. Length of female, 1.14 mm. 



88 (87) Setae of fifth feet of moderate length, last antennal segment with- 

 out hyaline plate Cyclops tenuis Marsh 1910. 



It has been found in Arizona and in the Isthmus of Panama. 

 Length of female, i . i mm. 



Fig. 1222. Fifth foot of Cyclops tenuis. X 272. (Original.) 



89 (81, 84) Second segment of fifth feet armed with three setae 90 



90 (91) With sensory club on twelfth antennal segment, hyaline plate of 



seventeenth antennal segment smooth or serrate, egg sacs 

 standing out from abdomen. . Cyclops albidus Jurine 1820. 



Fig. 1223. Cyclops albidus. A, abdomen of female. X 66. B, louitb loot of same. X I47i 

 C, fifth foot of sama. X 227. (Original ) 



