On Fresh -muter Crustacea. By Robert Gvrae.y. 283 



only were found under stones at the mouth of the spring Ai'n-el- 

 Hadjar (Sources d'Oumach) near Biskra. 



Spluvroma sp. — A species of Sph-seroma occurs in Lake Garaa 

 Achkel at Oued Tindja, but my specimens are not sufficiently 

 mature to be identified with certainty. They resemble S. serratwn, 

 which occurs abundantly along the shore of the Lake of Tunis (in 

 salt water). 



Gammarus simoni Chevreux. — This species was found to be 

 common at the mouth of the spring Ain-el-Hadjar (Sources 

 d'Oumach) about 10 kilometres west of Biskra. My specimens 

 differ in some respects from the description given by M. Chevreux, 

 but the differences are not of great importance. In my specimens 

 the accessory flagellum of the first antenna consists of two or three 

 joints ; the fourth segment of the abdomen bears a group of seta? 

 but no spines, the fifth and sixth being as described by M. Chevreux 

 with the addition of a few seta 1 . The telson differs in that there 

 is no lateral seta. In the form of the head and of the gnathopods 

 in both sexes there is complete agreement. It appears to be a 

 species widely distributed throughout Algeria and Tunisia, and 

 has already been recorded from the neighbourhood of Biskra. 



Gammarus pungens M. Edw.* — Found in a small rock-hewn 

 tank in the Gorge of the Bourn mel at Constantine. 



Gammarus locusta Linn. — A few specimens were found living 

 in fresh- water in Lake Garaa Achkel at Oued Tindja. 



Corophium volutator Ball. — A few specimens of this species 

 were found in the Oued Tindja at its outflow from the lake in 

 water practically fresh. The species seems to be very adaptable 

 with regard to salinity, since it is found also in Norfolk in places 

 where, for the greater part of the year, the water is perfectly 

 fresh. 



Entomostraca. 



Lcpidurus lubbucki Brauer. — A small number of specimens of 

 a species of Lepidurus were found on March 7 in some small pools 

 near Oued Tindja. Through the kindness of Canon Norman I 

 have been able to compare them with a specimen of L. lubbocki 

 fr<»m Sicily, and have no hesitation in identifying my specimens 

 with that species in spite of certain differences which I think it 

 advisable to mention. 



There appears to be a great variability with regard to several of 

 the characters of the species. The differences are as follows : — 



1. The nuchal organ is described by Brauer as "fast kreisrund," 

 whereas in Canon Norman's specimen and in my own the outline 



* My specimens of this and the preceding species have been submitted to the 

 Rev. T. R. R. Stebbing, who has been kind enough to examine them, and to con- 

 firm my identification. 



