CYCLOPS. 107 



5. CYCLOPS PULCHELLUS, Koch. PI. XVII, figs. 1 3. 



Cyclops pulchellus, Koch. Deutschlands Crust., H. xxi, t. ii (1841). 

 Sars. Oversigt af de indenlandske Fersk- 



vandscopepoder, p. 37 (1863). 



Body elongated, gradually tapered from above 

 downwards ; no marked separation between thorax 

 and abdomen ; the segments of the thorax, especially 

 the penultimate one, are produced and acuminated at 

 the posterior angles ; the last thoracic segment, how- 

 ever, is not angulated, and is scarcely broader than the 

 first abdominal ring. First pair of antennse about as 

 long as the first body segment. Abdomen slender 

 and gradually tapering ; caudal segments very slender, 

 five or six times as long as broad, and more than 

 equal in length to the last three abdominal segments. 

 Outer and inner caudal setse very short, the middle 

 seta of moderate length, equal to that of the abdo- 

 men without the furca, finely plumose ; a small 

 seta on the external margin of the furca below the 

 middle. Fifth foot 2-jointed (fig. 3) ; joints about 

 equal in size ; the first bearing one seta of moderate 

 length ; the second one long seta and a short spine. 

 " Ovisacs elongate-ovate and widely divergent" (Sars). 

 Length x^th of an inch (2*1 mm.). 



This is one of the rarer British species. The 

 following are the only localities in which I have 

 known it to occur : Bolam Lake and Paston Tarn 

 (Northumberland), and a pond at Tresco (Scilly). 



