286 Transactions of the Society. 



and ending in a sharp incurved point. In the branchial legs the 

 terminal plate of the endopodite (6th endite) is short and very 

 broad, with a rather well defined inner angle (plate VIII, fig. 4). 

 The fringing setae are short and spiniform on the inner margin. 

 The exopodite is large, oblong, and considerably longer than the 

 endopodite. Branchial appendix (flabellum) long and pointed, 

 coxal exite (bract) represented by two large lobes so deeply 

 divided from one another as to be nearly separate. 



Male : Body as in the female, but the abdomen is about equal 

 in length to the head and thorax together (plate X. fig. 12). 

 The head is produced into a short, blunt rostral process. Furcal 

 rami as in the female. Second pair of antennae small ; the basal 

 part is thick and hairy, and about equal in length to the succeeding 

 flexible part (plate VIII. fig. 3). The terminal part consists of 

 two subequal dactyli, each with a small rounded process on its 

 inner face at its base. Legs as in the female, but with the coxal 

 exite undivided. 



Measurements (average) : — 



Head and Abdomen. Furca. Egg-sac. Total Length. 



Thorax. 



Male . .. 7-7 mm. 7*5 mm. 1-8 mm. .. 17 mm. 



Female .. 8-1 „ 6-5 „ 2-1 „ 4-2 mm. 16-8 „ 



A few specimens of the species here described were found at 

 Oued Tindja in a pool in company with Lepidurus lubbocki and 

 Estheria cijcladoidm. Five females and one male only were pre- 

 served, the species is characterised by the simple form of the 

 antennae and egg-sac of the female, and especially by the form of 

 the branchial legs of the latter. In the Polyartemiidae and in most 

 species of Chiroc&phalus, the coxal joint of the leg bears two 

 foliaceous exites. In Chiroccphalus stagnalis the female may have 

 two exites, while the male has one, as in the species here described. 

 On the other hand, no species of Streptocephalus has yet been 

 described, so far as I am aware, which has the coxal exite at all 

 divided. 



Streptocephalus sp. — A single, not quite mature, female specimen 

 of a species of Strcptocephcdus quite distinct from the preceding one 

 was taken in a weedy pool a few yards away from that in which 

 the latter was found. As I assumed at the time that it belonged 

 to the same species, I made no effort to obtain more specimens. 

 As the specimen seems to belong to some undescribed species, 

 I give here a short account of it. 



The body is slender, the head and thorax somewhat exceeding 

 the length of the abdomen. The egg-sac has evidently not attained 

 its full development ; its extremity is bifid. The last segment of 

 the abdomen is somewhat wider than the preceding segment and 

 quadrangular in outline. The second pair of antennae are folia- 



