fiELONGESTG TO DAPHNIA. AND OTHER ALLIEB GENEEA. 241 



series of small, equal spines, about twenty-five in number ; ter- 

 minal unguis (fig, 9) smooth on its convex margin ; its concavity 

 finely ciliated, and towards tbe base bearing two sets of rather 

 stout spine-like setse. Shell polygonally reticulated (fig. 10). 

 Length, 2-5 mm. 



Male. — Shell seen from the side subrhomboidal in outline; 

 head flattened in front and without any beak (fig. 1), dorsal and 

 ventral margins subparallel, dorsal nearly straight, ventral very 

 slightly convex and trending upwards towards the hinder end ; 

 posterior extremity slightly narrowed and rounded off. Anten- 

 nules (fig. 2) two-jointed, truncated and slightly dilated at the 

 apex, which bears several small cilia and one long, stout, biar- 

 ticulate seta, the terminal portion of which is fringed with cilia. 

 First pair of feet (fig. 3) provided as usual with a long, stout 

 seta, a strong falcate hook, a branchial lamina with eight plumose 

 setae, and an intermediate small non-plumose seta. Abdomen 

 (fig. 4) destitute of dorsal processes ; post-abdomen wide and 

 obliquely truncated at the extremity ; marginal spines obsolete, 

 terminal unguis stout (fig. 5), finely ciliated and bearing near 

 the base two subcrescentic patches of stout setse : attached close 

 beneath the base of the unguis is a club-shaped appendage con- 

 sisting of a massive rounded protuberance, from which projects 

 downwards a stout handle-like process; the basal prominence 

 bears a few short teeth. Length, 1"4 mm. 



The whole animal in both sexes is densely pigmented, making 

 it very difficult to get a view of the structural details except by 

 dissection ; the limbs themselves are of an almost sooty black- 

 ness and the shell is brown. 



This interesting species has hitherto been found only in one 

 locality, — a pond on the road side about a mile west of Staithes, 

 Yorkshire. In this gathering (May, 1886) it occurred rather 

 plentifully, but I have seen only one male. 



Dactylura magna, Strauss, (PI. X., figs. 1-8, 18). 



1820. Daphnia magna, Strauss, Memoire sur les Daphnia de 



la Classe des Crustaces (Mem. de Museum, 



. Tom. Y., VL). 



