BYRNES: CYCLOPS OF FRESH WATER. 



The rami of the swimming feet are three-jointed. The armature 

 of the terminal segments is as follows: 



sa=seta in place of spine. ^One seta is minute, or represented b)' iiairs only, 

 the otlier is normal. 



Younger Sttnjcs of C. Sigjiatiis, var. Aiiiiulicornis. — From two 

 camera outlines of yonnger individuals it appears that the antennas 

 of aiiiiulifoniis can attain their maximum length in proportion to 

 the length of the hody, when they contain but eleven segments. 

 The basal joint of the fifth foot is likewise characteristically long 

 at this period, and the swimming feet show adult relations, as in 

 coroiatus. The immaturity of the form is indicated, however, by 

 its relatively small size, b}- uniform size among the abdominal 

 segments, by the incomplete number of segments in the antennae 

 and by the pale transparent appearance of the chitin. 



A still younger anmilicoruis shows ten-jointed antenn;e corre- 

 lated with two-jointed rami^ as in the form coronatus. The 

 second joint in the antennule is relatively long, and there are no 

 hairs on the inner surface of the caudal stylets. The distal segment 

 of the inner ramus of the fourth swimming foot lacks set?e on 

 the inner median surface, althotigli there are plainlv indicated 

 two regions where the hairs and setie usually appear in the later 

 stages. I was at first sceptical about the absence of setae in this 

 position, because characteristic spines and setae are usually to be 

 found well developed while the forms are still very young. But 

 the most careful search failed to give any evidence of broken sur- 

 faces, and I believe in this case the setae had never been developed. 

 It seems to me that the constant correlation of the characteristics 

 cited shows that we are here dealing with a form quite distinct 

 from C. coronatus. for the characteristics recur in all the stages of 

 the later molts. 



