24 



G. 0. SAKS. 



[No. 8. 



its edges. The length of the flagellum about equals that of the 

 pedimcle. 



The Ist pair of legs exhibit the usual structure, being modi- 

 fied to act as powerful claspers, with which the male grasp the 

 female during copulation. Their terminal part, with the strong, 

 curved hook and the slender bi-articulate seta, is often seen 

 exserted beyond the valves, wide-open in their anterior part. 



The tail is without any distinct dorsal processes, and has 

 the terminal part somewhat curved, with the anal margin slightly 

 incurved in the middle. Both the apical claws and the anal 

 denticles are relatively less fully developed than in the female. 



The testes are distinctly visible through the carapace, as 

 two narrow and somewhat flexuous tubes on either side of the 

 intestine, placed a little ventrally, and reaching forward to about 

 the insertion of the 3rd pair of legs. 



As regards colour, the body of both male and female is exceed- 

 ingly pellucid, with but a very faint greenish or yellowish tinge. 

 The developing ephippium appears at first rather translucent, 

 but very soon becomes quite opaque and of a dull greyish colour, 

 appearing in transmitted light almost black. 



Observations. — The movements of the animal would 

 appear to deviate somewhat at the different seasons of the year. 

 In the animals belonging to the earlier (summer) generations, 

 they are rapid comparatively, and without, in a strict sense, 

 being distinguished by that jerking or jumping peculiarity ob- 

 served in most other Daphniæ, but have more properly the 

 character of an even run through the water. During this 

 movement the animal retains its body in a somewhat oblique 

 position, with both the frontal spine and that of the carapace 

 pointing well-nigh horizontally. By rapid and quickly repeated 

 strokes of the antennæ, the animal propels itself with conside- 

 rable speed through the water, in the direction of the frontal 

 spine, and no perceptible deviation from the straight line can 

 be detected. Several times I watched specimens domesticated 

 in the largest of my aquaries, and invariably found them scud- 

 ding about, in the manner described above, through the whole 



