CYCLOPS. 105 



the length of the furca. Length rrth of an inch 

 (2-3 mm.). 



This species does not appear to be so common as 

 either of the foregoing. I have memoranda of its 

 occurrence only in three places, Belsay and Plessy 

 (Northumberland) and Seaton Marsh (Durham). 



4. CYCLOPS GIGAS, Glaus. PI. XX, figs. 1 16. 



Cyclops gigas, Glaus. Das Genus Cyclops (Weigmann's Archiv, 

 Band xxiii), p. 207, t. xi, figs. 1 5; Diefrei- 

 lebend. Copep., p. 100 (1863). 



Sars. Oversigt Ferskvandscopepoder, p. 35 (1863). 



Fric. Die Krustenthiere Bohmens, p. 220, fig. 14 



(1871). 



Anterior antennae (fig. 1) reaching to the third seg- 

 ment of the body, broadest at the base and mode- 

 rately tapered towards the extremity. Mandibles 

 strongly toothed (figs. 2, 3). Setae of the swimming 

 feet densely plumose beyond the middle (figs. 7, 8). 

 Fifth foot (fig. 9) 2-jointed; the basal joint exces- 

 sively broad and bearing a very long bristle at the 

 outer angle; second joint much narrower and armed 

 with a small spine and a long seta. The borders of 

 the abdominal segments are beset with rows of small 

 serratures or comb-like points; caudal segments 

 moderately stout, equal to more than the length of 

 the two preceding segments. Of the four strongly 

 plumose tail setae (fig. 10), the outer is much the 

 shortest and distinctly shorter than the furca; the 



