202 BRITISH ENTOMOSTRACA. 



In the female, as I have already mentioned, the second 

 niid third arc united; and running across its centre, we 

 may see a small canal which opens on each side where 

 the external ovary is given off, and in all probability fur- 

 uislies the envelope which contains the ova. This canal 

 has a direct communication with the internal ovary. 



The tail consists of two long lobes, making it appear 

 bifurcated, each lobe giving origin to four plumose setae, 

 the two intermediate of which are much the longest, and 

 have near the upper extremity a small joint, which adds 

 much to the suppleness of these fine organs. 



The internal ovaries are tolerably large, and divaricate. 

 The external ovaries, of the same colour as the adult, con- 

 tain in old females thirty or forty eggs on each side. The 

 length of this species is from f^th to fUh of an inch. 



The Cyclops quadricornis differs very much according 

 to age, locality, &c.* J urine enumerates seven distinct 

 varieties in the neighbourhood of Geneva. I have met 

 with several in the vicinity of London, which I have been 

 sometimes almost tempted to consider as distinct species. 



Var. a, elonyatus. Ramdohr's figure corresponds 

 exactly to this variety. It is of a dull gray colour, and is 

 of an elongate and narrow form. The thorax, abdomen, 

 and caudal segments, as well as the long filaments attached 

 to the tail, all partake of the same general elongate figure. 

 The antennae, however, are a little shorter than in the 

 other varieties. The segments of the thorax and abdomen 

 arc more distinct (t. XXIV, f. 3.) 



CYCLOPS QUADRICOUMS, luiniifuhr, Bcitragc, t. 1, f. 1. 



/\ <-/i, Dcutsch. Crust., h. xxi, t. 11. 



CYCLOPS AGILIS, Koch, 1. c., b. xxi, t. 3. 



Var. h. Jurine's figures of the vars. yv//;o/\, 

 and /-//vV//\ ji^rce with this variety. It may lie considered 

 the type <.!' the species. The thorax is more or less com- 



* " \ ,in:il Oolore albida, fuKr.srriiir, \iridi i 1 ) rulim." Mull., 1. c., p. 112. 



