NO. 1901. 



NOTES OX FRESH-WATER COPEPODA— MARSH. 



251 



posterior corners of the first and second segments in the female are 

 rounded, the third is either slightly produced backward or rounded, 

 while the fourth and fifth are produced outward and backward in 

 prominent points. The form of the fourth and fifth segments of the 

 cephalothorax is a marked characteristic of this species. The fifth 

 segment varies considerably in its form. Figures 2 and 3 show forms 

 from specimens collected near Damascus. Specimens from Axton 

 dui)Ucated these forms. The fourth and fifth cephalothoracic seg- 

 ments of the male do not have the characteristic form of those 

 found in the female. 



The first abdominal segment about equals in length the remaining 

 segments of the abdomen; the anterior end, while much narrower 



than the last cephalothoracic 



segment is nearly twice as wide 



as the posterior. The posterior 



margins of all the abdominal 



segments except the last are 



dentate; the last segment is 



armed with minute spines. 



Fig. 1.— Cyclops 

 strenuus, female. 

 X S6. 



Figs. 2-3.— Cyclops strenuus, 

 last cephalothoracic seg- 

 MENT. X "3. 



Figs. 4-5.— C y c l o p s 



STRENtraS. 4, FtTRCA OF 

 SPECIMEN FROM SYRIA, 

 fi, FURCA OF SPECIMEN 



FROM AXTON, New 

 York. X US. 



The branches of the furca are diverging, elongate, the length rela- 

 tively to the rest of the abdomen being variable, but frequently 

 equalUng the last three abdominal segments. The inner margin is 

 cihate, and running the length of the dorsal surface, there is a some- 

 what irregular cuticular ridge; this ridge is not found in males or in 

 immature specimens. The outer margin has an indentation at about 

 one-tliird its length, and the lateral seta is set well toward the end. 

 The terminal setae are rather short and weak. Figure 4 shows the 

 furca of a specimen from Syria and is t3q)ical in its structure. Figure 

 5 is from an Axton specimen and ditl'ers from the type in that it is 

 shorter, the lateral seta is set well back from the end of the segment, 

 and the cuticular ridge of the doi-sal surface is lacking; inasmuch as 

 no egg-bearing females were found in the Axton collections, it is 

 probable that the specimens were not quite mature. 



