1910.] FRESHWATER CRUSTACEA FROM THE TRANSVAAL. 149 



Weber)* used to come into my tow-net, when dredging through 

 the weeds ; this was the only fish I came across, and I was told 

 that no other existed there. I might also add, that an effort 

 had been made to introduce a large species of Barbel but 

 without success. 



Besides Lake Chrissie there are about a dozen other pans, 

 none however approaching that lake in size. The larger pans are 

 as a rule without reeds ; the smaller ones may be completely over- 

 grown. In the case of the former, the bottom may be composed 

 of sandstone with little or no mud present ; in the latter case, 

 fine mud is always present, very often of some depth. Very 

 few pans were at the time dry, but all of them, during certain 

 seasons after droughts, dry up completely ; most of them depend 

 for their supply of water on rain -fall ; others like Lake Chrissie 

 are furthermore fed by small spruits. Generally speaking the 

 water is somewhat brackish. 



As to local distribution, I found most species of Entomostraca 

 in Lake Chrissie ; but this result may be merely due to the fact 

 that since I had not the time to dredge all the pans very 

 thoroughly, I thought it best to pay most attention to Lake 

 Chrissie and to visit others but once or twice. 



A feature of interest among this entomostracan fauna is, that 

 out of the six species of Cypridse here described, in five 

 males and females were found in about the same proportion. 

 No doubt this interesting fact is correlated with the frequent 

 drying up of the pans, thus agreeing with the Cypriote of South- 

 West Africa as noticed by Vavra (11), and differing from their 

 European freshwater representatives in which males occur so 

 rarely that some species are known only by descriptions of 

 females t. 



The species collected throw some not altogether uninteresting 

 light on recent theories of distribution, and tend to confirm these 

 theories. This paper will, I think, have added some evidence in 

 favour of those who contend that South Australian, Tasmanian, 

 New Zealand, and South American forms have been independently 

 derived, perhaps through some Antarctic continent, from those 

 now found inhabiting South Africa ; I refer especially to a paper 

 recently read by Mr. C4. W. Smith (10). In this paper it is sug- 

 gested that such forms as the freshwater Gammarids and Isopods 

 or the genus Lepidurus, being essentially Crustacea preferring 

 a temperate or cold climate, found their way to South America, 

 and the Bassian subregion of Australia (Prof. Baldwin Spencer), 

 by spreading along the Andes and thence to Australia by some 

 lost Antarctic continental connection. Now no forms, typical 

 of these said regions, have as yet been described from South 

 Africa ; no freshwater Gammarids or Isopods are known to 



* I am indebted to Mr. G. A. Boulenger, F.R.S., for the identification of this 

 fish. 



f R. Moniez (5) first alluded to male Ostracods in Algeria appearing regularly 

 amongst those forms which in Europe propagate their species parthenogenetically. 



