1906.] OP THE NEW ZEALAND LAKES. 69T 



(fig. 2), the greatest width of the cephalothoi-ax scarcely equalling 

 one-third of its length, a distinct cervical sinus in front ; i.u'-osonie 

 very narrow, and, including the caudal rami, less than half the 

 length of the cephalothorax ; caudal rami short, scarcely longer 

 than the last abdominal segment, about twice as long as broad 

 (fig. 10). Anterior antennse very long and slender (fig. 3), reaching 

 as far as the extremities of the longest caudal setee, very sparingly 

 setiferous ; the two branches of the posterior antennfe (fig. 4) 

 nearly equal in length, the median joints of the outer branch very 

 small and indistinctly separate, three (or perhaps four) in number. 

 Mandibles and maxillae of the usual calanoid type ; anteiior 

 maxillipeds (fig. 5) very densely setiferous ; basal joint of the 

 posterior maxillipeds produced distally into a short, blunt, digiti- 

 form lobe ; second joint swollen, its inner margin rather strongly 

 arcuate (fig. 6). Swimming-feet long and slender, the basal 

 portion much elongated. Fifth pair bearing on the second joint 

 of the outer branch a strong marginal spine which reaches as far 

 as the apex of the last joint, this joint bears one long terminal 

 seta and two very short ones ; the inner branch is biarticulate and 

 bears terminal seta3 similar to those of the outer branch (fig. 8). 

 The ova are excessively large and very few in number — never 

 more than four (fig. 1). Length, exclusive of tail-setae, "SS mm. 



Male. The anterior antennae of the male (fig. 3) are geniculated, 

 but none of the joints is excessively enlarged or tumid, neither 

 are there any marginal serrations, though there are two not very 

 conspicuous spines on the 13th and 14th joints. The foot of the 

 fifth pair (fig. 9) on the right side has the outer branch ending in 

 a very long fiexuous spine, the inner branch short and simply 

 biarticulate ; the left foot has both branches simple and uni- 

 articulate, the outer branch curved, emarginate near the apex and 

 bearing a single terminal bristle, the inner branch much longer 

 and simply setiferous at the apex. 



Habitat. Abundant in a netting taken among reeds in Lake 

 "Waikare and in a "vertical netting" up to 120 feet. Lake 

 Rotoiti. 



I have much pleasure in naming this interesting species after 

 Mr. Keith Lucas, to whom I am indebted for the oppoiiiunity of 

 examining the proceeds of his painstaking investigation of the 

 New Zealand Lakes. 



Apart from its small size, this species proved unusually difficult 

 of examination owing to the tenuity of its tissues and the very 

 indistinct jointing of the various appendages, and I am by no 

 means sure that the account I have given is in all cases entirely 

 correct, as, for instance, in that of the swimming-feet, where some 

 specimens seemed to show doubtful traces of three joints in the 

 inner branches. 



Cyclops distinctus Jules Richard. 



Cyclops temdcornis var. distinctus Richard, Liste des Cladoceres- 

 ot des Copepodes d'eau douce observes en France (1887). 



