(is 



he has subsequently recognised its specific distinctness. As to its relation to the 

 2 other species, I think that it comes nearer to P. signatus than to P. annulicornis. 



Occurrence. The only place where I have as yet met with this form, is 

 in a small tarn near Christiansand. It occurred here, together with other Ento- 

 mostraca, near the bank on a muddy bottom covered with coarse gravel. All 

 the specimens observed were of a very dark bluish colour and in their whole 

 behaviour exhibited so great a resemblance to P. signatus, that at that time I 

 regarded them as merely belonging to a variety of that species, for which reason 

 I only made a coloured drawing of one of them, omitting to preserve the speci- 

 mens for further examination. The figures here given are from Swedish speci- 

 mens kindly sent to me by Prof. Wiren of the Upsala University. 



Distribution. Sweden (Lilljeborg), Germany (Schmeil), France (Richard), 

 Poland (Lande). 



40. Paehyeyelops annulicornis (Koch). 



(PI. XLII). 



Cyclops annulicornis, Koch, I. c. Heft 21, Tab. 6. 

 Syn: Cyclops qvadricornis albidus, Juvine. 

 tenuicornis, Glaus. 



albidus, Schmeil. 



gyrinus, Forbes. 



Specific Characters. Female. Anterior division of body broadly oval in 

 outline, greatest width exceeding half the length and occurring somewhat in front 

 of the middle. Tail comparatively more slender than in the 2 preceding species, 

 somewhat exceeding half the length of the anterior division; genital segment of 

 about the same shape as in P. signatus. Caudal rami comparatively short and only 

 slightly diverging, inner edge scarcely ciliated; apical setae less densely plumose 

 and less spreading than in the 2 preceding species, the inner mediate one almost 

 attaining half the length of the body; seta of outer corner comparatively short, 

 scarcely exceeding in length Vs of that of the inner corner. Anterior antennae 

 long and slender, reaching, when reflexed, beyond the 3rd segment, outer joints 

 very narrow and exhibiting a well-defined lateral rib, which is quite smooth through- 

 out, and projects at the end in a small lappet. Posterior antennae with the 

 terminal joint much longer and narrower than the penultimate one. Maxillipeds 

 about as in P. bistriatus. Natatory legs likewise very similar; terminal joint 

 of inner ramus in 4th pair, however, distinguished by the quite rudimentary con- 

 dition of the distal seta of inner edge; apical spines of this rarnus slightly une- 

 qual, the outer one being the larger. Last pair of legs of almost exactly the same 

 shape as in P. signatus, the distal joint being conspicuously smaller than the 



