1885.] 



CLADOCERA. 



33 



of ephippium not uncommonly found at first in the dried mud, 

 and one of whick is represented in Pl. 1, fig. 14. 



Description of the Male. — The size of the full-grown 

 male of this species is very much inferior to that of the female, 

 measuring only 0,63 mm in length. 



The general form of the body (see Pl. 6, fig. 3) appears 

 somewhat dissimilar from that of the female, being by far not so 

 clumsy, and rather slender and compressed. 



The head is comparatively more erect and elongate, with 

 the dorsal face less arched and the sinus above the eye shorter. 

 The front is evenly rounded, and the ventral margin exhibits at 

 the point of insertion of the antennulæ a gentle curve. 



The carapace has the dorsal part not in the least expanded, 

 and is abruptly truncate posteriorly, with the upper angle well- 

 nigh a right one, the lower corner rounded. 



The antennulæ are enorm ously devel oped, attaining about the 

 length of the head, and are exceedingly mobile. They appear, 

 as it were, geniculate, the slender distal part forming a slight 

 angle with the proximal, without however being marked off by 

 any perceptible suture. At the junction of the two, are affixed 

 anteriorly two unequal setæ, the one very small, whereas the 

 other is rather elongate, and would appear to correspond to 

 the tentacular seta in the female antennulæ. The distal part 

 being almost twice as long as the proximal, bears at the apex, 

 exteriorly, a small bunch of sensory papillæ, and interiorly, 3 

 strong incurved hooks (see fig. 4). Of any true flagellum no 

 trace whatever can be detected. 



The Ist pair of legs (fig. 5) are modified in the usual man- 

 ner as powerful claspers, the exterior part being incrassated and 

 containing several converging muscles, that move the very strong 

 anteriorly curved hook. At the base of this hook, is seen anteri- 

 orly a very short seta, and posteriorly, a thin plate bearing 3 

 plumous setæ of equal length. 



The tail would not seem to exhibit any marked difference 

 from that in the female. 



The testes occupy their usual place, and agree in struc- 



Vid.-Selsk. Forh. 1885. No. 8. 3 



