EEESH-WATER CYCLOPID.E AND CALANIDJ2. 9 



caudal rami slightly divergent, nearly as long as the preceding 

 three segments, each marked by a longitudinal ridge, which is 

 continued faintly over the last abdominal segment; the two 

 principal setae are of nearly equal length, the inner somewhat 

 the larger, but shorter than the abdomen, and more than twice 

 as long as the neighbouring lateral seta ; outer lateral more than 

 half as long as the inner ; marginal seta situated near the ex- 

 tremity of the furca : the posterior margins of the abdominal 

 segments are obscurely dentated except the last, which bears a 

 series of minute hairs. Anterior antennae slender, reaching back- 

 wards to the third segment of the body, and provided plentifully 

 with setae, especially towards the base. Posterior antennae long 

 and slender, the posterior margins of all the joints bearing 

 patches of short hairs arranged in a pectinate manner; while 

 the third joint has its anterior margin armed with a series of six 

 moderately long, equal setae, besides the usual apical hairs. 

 Branches of the swimming feet all three-jointed and nearly 

 equal in length, except in the fourth pair, where the inner 

 branch is distinctly the longer : in the first and second pairs 

 the marginal spines of the last joint of the outer branch are 

 three in number, in the third and fourth pairs only two : the 

 inner branch of the fourth pair has the last joint prolonged 

 externally, forming a process about half as long as the terminal 

 spine. Fifth foot composed of two nearly equal joints, first joint 

 with one seta of moderate length, second with one long and one 

 short seta. The animal is almost colourless. Length about 

 2 mm. 



Taken in gatherings made by the deep net in "Windermere and 

 Coniston Water, but by no means plentiful: August, 1883. 

 Prof. Gr. 0. Sars has kindly examined specimens from one of 

 these localities and identifies them as belonging to C. ahyssorum. 

 It occurs also in gatherings from Loch Awe, Loch Ness, Loch 

 Achray, and Loch Lomond, Scotland; and in Broomley Lough, 

 Northumberland {Rev. Br. Norman). The foot-jaws do not pre- 

 sent any characteristic features. This species has hitherto been 

 recorded only by Prof. Sars, who found it at a depth of 40-50 

 fathoms in Maridals- water near Christiania. 



74 



