24 A REVISION OF THE BRITISH SPECIES OF 



jointed, slender, much shorter than the first cephalothoracic 

 segment, the first, seventh, and eighth joints being the longest; 

 the second, fourth, and sixth the shortest. All the pairs of 

 swimming feet have both branches two-jointed, and the last 

 joint of the outer branch bears three lateral spines. The fifth 

 foot is quite rudimentary, consisting, on each side, of two simple 

 spine-like setae with slightly dilated bases. Length 1*1 mm. 



This very interesting form, which seems not to have been 

 previously noticed except by Poggenpol (environs of Moscow), 

 I have seen only in very small numbers, in a gathering made 

 by Mrs. Tupper Carey, at Ebbesburne, near Salisbury, and 

 communicated to me by my friend the Rev. Canon Norman. 

 Poggenpol's measurement of length is rather greater than mine 

 (1*39 mm.), but apart from this there does not seem to be the 

 slightest discrepancy. The description of the Eussian speci- 

 mens, however, does not refer at all to the number of joints in 

 the rami of the swimming feet : this is an important point, the 

 two-jointed forms being of extremely rare occurrence. C. bicohr, 

 Gr. 0. Sars, is a very much smaller species, but, judging from 

 the description, agrees very closely with C. longicaudatus, and 

 has, moreover, the two-jointed feet: it disagrees, however, in 

 some minor points, such as the arrangement and size of the 

 caudal setae, on which Professor Sars is very explicit. It may 

 be added that, though I have seen no specimens with ovisacs, the 

 Salisbury specimens have every appearance of perfect develop- 

 ment, and I have no doubt at all that they are quite mature. 



e. Anterior antenna ten-jointed. 

 17. Cyclops Kaufmanni, Uljanin (PI. VII., fig. 3). 



1875. Cyclops Kaufmanni, Uljanin (28), p. 38, pi. XII., 



figs. 2-4. 

 1878. „ „ Brady (32), p. 113, pi. XXIV., 



figs. 6-12. 



This is a very well-marked species, characterised chiefly by 

 the ten-jointed antennae and the strongly pectinated margins 

 of the abdominal and posterior thoracic segments. The only 

 British locality for it known to me, at the time of publishing 

 the Kay Society Monograph, was Lambton Park, county Durham, 



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