685 



South Africa owe some part of their periodicity to a direct connection 

 with the sea. The obstacles to a colonisation of such waters would 

 consist only in apparent scarcity of food and difference of salinity. 

 Scarcity of food cannot have much influence , as the fact that animals 

 do live in these situations shows that food is there. The difference of 

 salinity is, I believe, of less importance as a barrier to the colonisation 

 of fresh water than differences and fluctuations of temperature and 

 pressure. Experiments hitherto made on the acclimatisation of marine 

 animals to lowered salinity are not of very great weight in this con- 

 nection, since it is important to know, not what degree of salinity an 

 animal can be exposed to without dying, but what it can live and repro- 

 duce in. In Northern countries few marine species have established 

 themselves in fresh water and these, (e. g. Mysis relicta) inhabit deep 

 lakes almost exclusively, whereas, in tropical countries, a large number 

 of such species are found both in lakes and rivers. The difference of 

 salinity must be the same , but the fluctuations of temperature would 

 be less in tropical regions. In passing from a marine habitat, below 

 the reach of the tide, to a subterranean fresh water habitat, a Crusta- 

 cean would be entering a medium subject to a very uniform temperature 

 and rather high pressure, similar, in these respects, to that in which it 

 was accustomed to live , and having the advantage of being in a region 

 of slight competition. This Algerian species may perhaps be supposed 

 to have arisen from some deep water Mediterranean species such as 

 Cirolana caeca Dollfus. 



7. Über eine neue Blattidengattung, aufgefunden in Südwestafrika. 



Von H. Karny, Wien. 



eingeg. 4. Januar 1908. 



Genus I*seudogynopeltis m. 



Genus nov. vie. Gynopeltis Gerst. 



Vertex obtectus. Pronotum margine postico truncato. Mares com- 

 plete alati, elytris alisque ad marginem anticum ante apicem macula 

 opaca, non pellucida ornata. Feminae apterae vel rudimentis elytrorum 

 lobiformibus, mesonotum vix superantibus. Femora omnia mutica. Ti- 

 biae longe spinosae; posticae supra triseriatim spinosae. Tarsi longi, 

 graciles; metatarsus posticus articulis reliquis simul sumptis longior. 

 Cerci çf graciles, laminam supraanalem superantes, Q. brevissimi. 



Die neue Gattung, die mir in mehreren Arten vorliegt, ist dadurch 

 interessant, daß sie eine Mittelstellung zwischen Gynopeltis und der 

 indischen OlyptopcUis einnimmt. Die Unterschiede von diesen beiden 

 Gattungen sind aus der gegebenen Beschreibung leicht zu ersehen. Die 



