1885.] 



CLADOCEEA. 



23 



that of ephippia bearing females. And I did succeed, after 

 some little trouble, in lighting among the numerous female speci- 

 mens upon a few fully developed males, the examination of which 

 has enabled me to give a more complete description of the 

 present interesting species. 



Description of the Male (Pl. 3, fig. 3). — The size of 

 the full-grown male, is, as usual, much inferior to that of the 

 female, not exceeding 1,60 mm, and its general habitus, as also 

 the structure of certain of its limbs, very dissimilar. 



The head appears much more depressed, the frontal part 

 being obtusely rounded off and somewhat projecting inferioriy, 

 with only a very slight knob-like rudiment of the frontal pro- 

 lation. The ventral part of the head is, as it were, cut off, not 

 forming even a trace of a rostral projection. 



The carapace occurs comparatively much narrower than 

 in the female, the dorsal part not the slightest arched, nor 

 the free edges of the valves exhibiting any regular curve. 

 A little in front of the middle the latter appear strongly in- 

 flected, forming anteriorly a salient angular projection. This 

 projection, as also the inflected part of the valves, are edged 

 with a dense fringe of delicate plumous setæ. The spine of the 

 carapace, finally, is somewhat short and obliquely upturned. 



The eye would appear to be a trifle larger than in the 

 female, almost filling up the rounded frontal part. 



The antennulæ are very dissimilar from those in the female. 

 and comparatively stronger developed than in the males of our 

 Northern species, fully attaining, as they do, the length of the 

 head. They are very mobile, and articulated with two small 

 rounded prominences at the infero-posterior part of the head, 

 being, as a rule, directed straight downward, and somewhat diverg- 

 ing. Their basal part, jor peduncle, is narrow-cylindric, and 

 contain within its proximal part a strong muscle; at the end, it 

 exhibits posteriorly a rounded prominence, to which are affixed 

 the usual sensory papillæ, whereas, in front of the prominence, 

 protends the slender setiform flagellum, composed of two articu- 

 lations, the outer very delicate and finely ciliated along one of 



