On Fresh-water Crustacea. By Robert Guriicy. 287 



ceous, hairy, and with a small pointed process in the middle of 

 its rounded end (plate IX. fig. 6). The branchial legs are of the 

 usual form, the terminal plate more or less rectangular, and the 

 exopodite very much longer than the endopodite in the legs of 

 the middle of the series. At the base of the setae of the distal 

 margin of the exopodite is a small bifurcated spine (plate IX 

 fig. 7). 



Measurements : — 



Head and Thorax. Abdomen. Fnrca. Total. 



7-0 mm. 6-5 mm. 1-6 mm. 15-1 mm. 



Esthcria cycladoides Joly. — Abundant at Oued Tindja and at 

 Sidi Athman. Numbers of larvre, probably belonging to this 

 species of Estheria, were found in an irrigation pool in Biskra. 

 According to M. Signon it is widely distributed in North Africa 

 and occurs also in Southern France, Spain and Sicily. 



Daphnia atkinsoni Baird. — This species was not found in 

 Algeria, though its ephippiuin was noticed in a collection taken 

 in Chott Tinecilt while the train stood in Les Lacs station. In 

 the neighbourhood of Tunis it was a common occurrence. In small 

 pools surrounding Lake Sedjouma by Tunis it was found in water 

 having a very high salinity, the density of which varied from 

 1 • 007 to 1 • 035. It was also found in various small pools at Sidi 

 Athman, Oued Tindja, and St. Germains. 



While none of the specimens seen are referable to the variety 

 bolivari Bichard, many, and particularly young individuals, show 

 a distinct transition towards it, having a pronounced dorsal cephalic 

 ring which, in some young individuals, is provided with very minute 

 spines. Some specimens taken at Sidi Athman have the dorsal 

 cephalic ring very distinct but not spinous, while the anterior part 

 of the fornix of the valves is provided with spines as in D. bolivari. 

 Males and ephippial females w r ere found on five occasions out of a 

 total of twelve occurrences. 



Daphnia chevreuxi Bichard. — Found in some numbers at Oued 

 Tindja and also at St. Germains. Males and ephippial females 

 were found on the first occasion. 



Whereas in the adult female the head is more or less square 

 in outline, in the young of both sexes the anterior margin of the 

 head slopes upward, meeting the dorsal margin in a sharp, back- 

 wardly projecting peak. On the dorsal side just behind this peak 

 there is a small oval disk resembling the nuchal adhesive organs 

 of certain other Cladocera (plate X. fig. 11). The two dorsal 

 rows of spines are continued up to this point, enclosing the 

 posterior half of the disk between them. In the adult both disk 

 and dorsal peak generally disappear, but an ephippial female from 

 Oued Tindja still showed a slight protuberance in the position of 

 the peak. The arrangement of the dorsal spinules in a curve 



