194 ESTHER F. BYRNES. 



Third Foot. Fourth Foot. 



The rudimentary fifth foot was two-jointed, having an almost 

 square basal segment bearing an immature seta on its outer distal 

 angle, and a slightly elongated distal segment bearing three 

 hairs. 



The larger cyclops, Plate VIII., combined the following charac- 

 teristics : the antennae contained eleven segments ; the rami of 

 the swimming feet were three-jointed with an adult armature, as 

 follows : 



First Foot. Second Foot. 



Outer Ramus. Inner Ramus. Outer Ramus. Inner Ramus. 



3 outer spines, i outer seta, 3 outer spines, I outer seta. 



I apical spine, I apical spine, I apical spine, I apical spine. 



I apical seta, I apical seta, I apical seta, I apical seta. 



3 inner setae, 3 inner setae, 4 inner setae, 3 inner setae. 



Third Foot. Fourth Foot. 



Outer Ramus Inner Ramus Outer Ramus. Inner Ramus. 



3 outer spines, I outer seta, 2 outer spines, I outer seta. 



I apical spine, I apical spine, I apical spine, I apical spine. 



I apical seta, I apical seta, I apical seta, I apical seta? 



4 inner setae, 3 inner set?e, 4 inner setae, 2 inner setae. 



The rudimentary fifth foot was two-jointed with an almost 

 square basal segment, bearing an immature seta externally, and 

 a distal segment, longer than broad, armed with two immature 

 spines and a median seta. 



The study of a large number of these forms showed that both 

 forms were always found together; that they always accompanied 

 C. signatus, var. coronatns, having seventeen antennal segments ; 

 that in the absence of strong color markings and hairs they gave 

 evidence of being young ; and that they were, as a rule, sexually 

 immature, although the larger cyclops occasionally contained 

 ova. I became convinced of their larval character, as well as of 

 their relationship to C. signatns, and determined to test the cor- 

 rectness of the conclusion by breeding experiments. Accord- 

 ingly, a few fertile females with appended embryos, were isolated 

 in a carefully prepared aquarium. At the end of two months 

 this aquarium was examined for the desired forms, when nu- 



