28 Mr. E. Gurney on sjme Freshwater 



circle of reticulations which do not extend over the egg- 

 space itself (PI. II. fig. 1). The male resembles that of 

 M. rectirostrls in shape and in the form of the first leg and 

 first antenna^, but differs from it in having only three hooks 

 at the end of the first antenna (fig. 2). Tiie number of 

 these hooks does not ai)pear to be quite so constant a 

 character as has been supposed, as I have shown (1909) that 

 a form of M. redirostris occurs in Tunisia in which the male 

 has only four hooks in place of five. It appears, therefore, 

 that the diff'erences between the species in question and 

 Moina rectirostrls are : — 



(1) Its small size. 



(2) Small number of teeth on the postabdomen. 



(3) Less pronounced comb on the postabdominal claws. 



The presence or absence of transversely arranged 

 cilia on the postabdomen has been shown by Ekman 

 not to be distinctive. 



(4) There is a slight difference between the proportions in 



the two species between the prceanal and postanal 



parts of the postabdomen. 

 The first three of these differences seem to me to be 

 probably accountable by the limnetic habit of the species, 

 and the sum of the differences does not seem to amount to 

 specific distinction. 



(13) Moina salinarumy Gurney. (PI. 11. figs. 3, 4.) 



In the plankton of the Birket el Kurun a species of Moina 

 which is identical with that recently found by me in a salt 

 lake in Tunisia, and described under the name M. salinarum, 

 is abundant. There is no perceptible difference between the 

 two, except that I cannot detect in the Egyptian specimens 

 any cilia on the first pair of antennae. I give a figure of the 

 postabdomen for comparison (fig. 3). I have nothing to add 

 to the description already given, except that the first leg of 

 the female agrees in all respects with that of M. rectirostrls. 



No ephippial females were found, but a few males occurred 

 in a collection made in the Lake on Feb. 20, 1909. These 

 males do not differ in any important respect from those of 

 M. rectirostrls, though the head is somewhat longer and more 

 conical and the depression above the eye is very slight. The 

 form of the first leg is also the same. On the other hand, 

 the shape of the postabdomen diflers in the same way as does 

 that of the female, and the first antennae bear four hooks 

 instead of five. In one male a distinct trace of a pigmented 

 ocellus was seen (fig. 4). 



