26 COLD SPRING HARBOR MONOGRAPHS. Vll. 



chcllus. In C. biciispichitiis the caudal stylets are relatively shorter 

 and more delicate than in the other members of the viridis type. 



Forbes records having found intermediate forms of Cyclops 

 that bridge the gap between C. bicitspidatiis and C. pnlclielltis, variety 

 Naviis (Herrick). He also states that there is no need of con- 

 sidering C. thomasi even as a variety. Forbes finds C. hicnspidatns 

 very widely distributed in America and subject to a very wide range 

 of variation : It is a common pelagic form but is found also in 

 ponds. 



Life in ponds, according to this author, tends toward the develop- 

 ment of more robust forms; while the more slender forms are 

 found in the deeper waters of lakes. In the Long Island collec- 

 tions, I have encountered this form in a very limited locality in a 

 ver\' shallow pool abundantly filled with water plants. Collections 

 have usually been made in this locality in the spring, when it is 

 characteristic of the form to become sexually mature while the 

 antennae contain but thirteen segments (Fig. 5, Plate X.), although 

 ultimately the antennas acquire seventeen segments (Fig. 4, 

 Plate X.). 



Cyclops Modestns (Plate XL, Figs. 4 and 5). 



This is a comparatively small species with very characteristic 

 color markings. The whole body is suffused with a pinkish tint 

 while the swimming feet are strongly colored a deep purplish red. 

 This color belongs rather to the chitin than to the protoplasm and 

 persists for many months in specimens preserved in glycerine. 

 C. modestus was found at Cold Spring Harbor in shallow spring 

 fed ponds. It was especially abundant in collections made from the 

 bottom in the summer of 1905, though collections made from this 

 same locality in previous years contained no Cyclops of this species. 



In general morphology the Cold Spring Harbor form agrees 

 with Professor Marsh's description of C. modestus, found in the 

 region of the Great Lakes, but it differs in some details from Pro- 

 fessor Herrick's account of C. modestus. The fifth foot is very 

 distinctly three-jointed not "obscurely" as Herrick observed. 



The antennae are characterized l)y greatly elongated hairs on the 

 first, second, fifth, tenth and thirteenth segments, although several 

 of the other segments also produce long hairs. 



The armature of the swimming feet is as follows : 



