Am/phipoda baloanÍGa. 105 



localities, which are far from one another, i. e. in North 

 Germany, North and South Poland, Moravia, Montenegro. 

 The representatives of this cycle, with the blind forms 

 Boruta tenehrarum and Crangonyx suhterraneuSy are the rem- 

 nants of a large old f amily from the cold, perhaps ice period. 

 Tn the warmer period the most of these forms died out, 

 some of them immigrated in the springs under the surface 

 and were the origin of the blind forms. Only few forms re- 

 mained in the waters of the nether and npper world. That 

 also the S. amhulans is inclined to lose the eyes demonstrate 

 very few ommatidia in the eyes of this form [Ct. relicts]. 



c) Forms, which formerly occurred very 

 often and were later pushed to a fixed loeality, 

 from where they returned in the runs: 



One of these forms is Carinogammarus roeselii. This 

 form, though a Carinogammarus species, is very near to 

 G. pulex. This relation is manifested by the samé form of 

 brood plates. We can suppose that C. roeselii occurred in 

 the preglacial period very often. But with the glacial period 

 it was perhaps going to the low localities in the vicinity of 

 the sea. With the warmer climate after the glacial period 

 C. roeselii was progressing through the rivers in the European 

 continent. A very easy way this species found in the Da- 

 nube. The Elbe has not been so adapted to the immigration 

 of this form, because we cannot find it in Bohemia, in špite 

 of Bohemia being in the Elbe district. Perhaps the greatest 

 obstacle for C. roeselii in the Elbe river has been the f ormer 

 store cataract in Saxony near the Bohemian frontier. 



d) Very old ubiquitary forms: 



The oldest are the forms of the cycle G. pulex i. e. 

 G. pulex-spinicaudatus-halcanicus-komárehi. All these forms 

 are descendants of G. locusta, which lives everywhere in 

 Europe and Asia in all the localities not so easily acces- 

 sible for these forms. 



The form G. homáreki is the representative of an Asiatic 

 branch of the cycle G. pulex. But it came to Europe, before 

 the straits of the Dardanelles were formed. 



