BYRNES: CYCLOPS OF FRESH WATER. 



33 



The receptaculum seminis is very characteristic, appearing as 

 two broadly oval masses (Fig. 2, Plate XIV.). 



Cyclops Fiiiibnatns, Fischer (Plate XV.). 



Cyclops fimbriatns has been taken in great numbers in some of 

 the collections made in the Long Island waters, especially in col- 

 lections made in the early spring. At other seasons it has been 

 found only sporadically. 



The form figured in Plate XV. was found in Jamaica. Long 

 Island. It agrees so closely with Herrick's description of fimhria- 

 tiis in his report on the Entomostraca of Minnesota, that little 

 further account need be given of it. The variations noted are 

 slight and unimportant. 



The characteristics of C. Umbriafus are as follows: 



The antennas contain but eight segments: they are short and are 

 characterized by two well developed setse. 



The spines and setre of the swimming feet are without any 

 well defined character, although the sexual maturity of the form 

 implies that it is fully developed. The armature of the terminal 

 segments of the swimming feet is as follows: 



Foot No. 



Ramus, Outer or Inner. 



O 



Outer Spines 3 



Apical Spines 



Apical Seta 2 



Inner Set:e 



II 



III 



11 

 1 

 1 

 3 



IV 





 2 



^seta. %eta. ^large. ^unequal. 



The inner margins of the swimming feet are strongly serrated 

 and hairy. The fifth foot is one-jointed and bears a coarse inner 

 spine and two setae. Herrick states that the fifth foot bears three 

 spines. 



The most striking variation iii C. Hmhriatus is a tendency toward 

 a reduction in the armature of the inner ramus of the first swim- 

 ming feet, where in the apical position, for example, a single large 

 spine replaced two setcX or a spine and a seta which is the tvpical 

 armature of the organ. 



