

much prolonged, 1st pair with a single seta on the anterior border of the basal 

 joint, 2nd pair with 2 such setae, last pair with no seta on this border. Caudal 

 lamellae very small and simply rounded, without any marginal bristles. Copu- 

 lative appendages of male distinguished by a very conspicuous dark-coloured 

 string issuing from the lower face of the basal part and more or less spirally 

 convoluted at the base. 



Remarks. This genus was established in the year 1865 by the present 

 author, and has been admitted by all subsequent authors in the sense originally 

 adopted. The generic name alludes to the peculiar protuberance of the hind 

 extremity of the shell found, more or less distinctly defined, in all the known 

 species. The genus is very rich in species, most of them being found in 

 rather shallow water among algae. In the succeeding pages 12 species refer- 

 able to this genus will be described, and Norman has also recorded from the 

 Norwegian coast a few other species not yet observed by me. 



98. Cytherura gibba, (O. Fr. Muller). 



(PI. XCIII). 

 Cythere gibba, O. Fr. Muller, Entomostraca, p. 66, PI. VII, figs. 7- 9. 



Syn: Cythere gibbera, O. Fr. Muller (male). 

 Robertsoni, Brady $ . 



Specific Characters. Female. Shell rather tumid, seen laterally oblong 

 subreniform in shape, scarcely higher in front than behind, greatest height 

 about equalling half the length, dorsal margin only slightly bent in the ocular 

 region and perfectly straight in the middle, joining the hind margin by a quite 

 gentle curve, ventral margin distinctly sinuated in front and somewhat bowed 

 behind, anterior extremity broadly rounded, posterior gradually contracted to 

 an obtuse protuberance located in the longitudinal axis of the shell; seen 

 dorsally, broadly ovate in outline, with the greatest width behind the middle 

 and rather exceeding half the length, side-edges abruptly bowed behind, both 

 extremities sharply pointed at the end, the anterior somewhat narrower than 

 the posterior. Valves only slightly unequal, each exhibiting behind the middle 

 a very conspicuous rounded tuberosity, surface otherwise quite evenly convex, 

 without any obvious folds, but with indication to a faint reticulate pattern; 

 edges smooth and clothed with scattered hairs. Eyes comparatively small, but 

 well observable in fresh specimens. Anterior antennae with the terminal joint 

 rather prolonged, being fully as long as the preceding joint. Posterior antennae 

 comparatively slender, with the penultimate joint distinctly subdivided in the 

 middle by an oblique suture. Legs of moderate length. 



