CYCLOPS. 117 



much attenuated towards the apex ; shorter than the 

 first segment of the body, 10-jointed ; the second, 

 fourth, fifth, seventh, and eighth joints are very 

 short; first, sixth, and tenth the longest (fig. 7). 

 Posterior antennse robust, with short joints. Fifth foot 

 (fig. 12) reduced to a single wide and short process, 

 which bears three subequal ciliated spines, the inner 

 border of the thoracic segment to which it is attached 

 bearing a row of about twelve small spines or 

 serratures. Mouth organs small. Abdomen not dis- 

 tinctly narrower than the cephalothorax, tapering 

 very gradually towards the extremity ; last segment 

 very short. Caudal rami subconical, about twice 

 as long as broad (fig. 13), and beset with small spine- 

 like hairs ; tail setse beset with very short marginal 

 cilia; the innermost of the two principal setae much 

 the longest. Length ^th of an inch (1 mm.). 



G. jphaleratus is one of the less common British 

 species, and likewise one of the most distinct and 

 most easily recognised. The following are the 

 localities in which I have found it : — Ormesby Broad 

 (Norfolk), Bolam and Sweethope Lakes (Northumber- 

 land), ponds at Gibside (Durham), Kinny Lough 

 (Co. Donegal), and near Westport (Mayo) : canal at 

 Peterhead (Mr. D. Robertson). 



