BYRNES: CYCLOPS OK FRESH WATER. 13 



both varieties — in short in the most important differential charac- 

 ters of the two varieties. 



Cyclops Aiiiencaitns, Marsh (Plate V., Figs. 1-3). 



Any one who studies the fresh water Cyclops will note that 

 underlying the many diverse forms under which they appear, there 

 are easily recognizable types to which many of them may be 

 referred. One of these types is represented in C. viridis. The 

 viridis type is characterized by a relatively long slender body that 

 tapers gracefully from the cephalo-thorax to the caudal stylets. 

 The antennae contain seventeen segments and reach nearly to the 

 posterior margin of the cephalo-thorax. The caudal stylets bear 

 but two long sets and the fifth foot is two-jointed: the basal seg- 

 ment may vary in breadth, but it carries a single seta on its outer 

 angle. The distal segment may likewise vary somewhat in length 

 and breadth, but it carries an apical seta and a spine on its inner 

 angle. Sometimes the spine is well developed but often it is 

 very diminutive. The striking features of the type are illustrated 

 in a general way by Fig. i and Fig. 3 of Plate V., C. Americanus , 

 Marsh (C insectus, Forbes). 



C. Americamis is a relatively large Cyclops found in different 

 localities — in sphagnum swamps, in stagnant water and in fresh 

 water lakes. It is one of the most widely distributed forms encoun- 

 tered in the Long Island waters. 



The characteristic distinctions by which C. Americanus (Marsh), 

 can be identified among the various members of the viridis type 

 are to be found chiefly in the armature of the swimming feet which 

 agree in every detail with Marsh's description of them (Plate 

 v., Fig. 2; cf. feet of C. parens, Plate VI., Fig. 3). 



Foot No 



Ramus, Outer or Inner 



Outer Spines 



Apical Spines 



Apical Seta" 



Inner Setfe 



II 



III 



I 



1 (sa) 

 1 

 1 

 3 



I 



l(sa) 

 1 

 1 

 3 



I 



1 (sa: 

 1 

 1 

 3 



IV 



l(sa) 

 2 





 



