504 FRESH-WATER BIOLOGICAL STATIONS OP THE WORLD. 



It is furthermore clear, from what has been previously said, that such 

 permanent stations are of two distinct classes. First, those which may 

 be denominated general, even though their work is of the greatest 

 value for special purposes, and, second, those which are distinctively 

 technical by virtue of their association with specific enterprises. 



It is but natural that the different continents are very unequally 

 represented with regard to the number of stations that have been 

 established upon them, and with respect to the knowledge that has 

 been gained in reference to their fresh-water fauna and flora. Thus, 

 our knowledge of the Australian fresh-water fauna is confined at present 

 to the report of collections made by travelers, and to the investigation 

 of specimens raised by Sars from dry mud which had been sent to him. 

 Of Africa we know that fifteen years ago an expedition brought word 

 from Lake Tanganyika that while rowing across its waters they encoun- 

 tered swarms of jelly-fish, while many of the gastropod shells which 

 were brought back with them showed in an equally striking way their 

 marine character. These reports have been confirmed by an expedition 

 that has just returned, and the strikingly marine complexion of the 

 fauna of the lake can hardly be doubted. This appears all the more 

 strange since collections made at Lake Nyassa, which lies decidedly 

 nearer the sea, show nothing but what is specifically lacustrine. Such 

 facts point, of course, to the importance of the African fresh-water 

 stations of the future. 



From various lakes of Asia, all the way from Ceylon to Siberia, 

 numerous more or less extensive collections have been made by trav- 

 elers, though there is hardly anything sufficiently extended to warrant 

 the statement that a station has been located, even for a limited time, 

 at any point, especially since most of the collections have not been 

 investigated by men who had made them, but have been turned over as 

 alcoholic material to European investigators for study. We do know, 

 however, that Lake Baikal, which is situated almost in the center of the 

 continent, harbors a rich molluscan and crustacean fauna that is char- 

 acteristically marine in its form, and is further distinguished by posses- 

 sing many sponges clearly of marine type, and at least one species of seal 

 (Phoca), a genus which is typically oceanic. A discussion on the mean- 

 ing of these features lies far from the purpose of the present paper, but 

 certainly such facts do point out most strikingly that the field of limno- 

 biological investigation is not lacking in topics of extreme interest. 



From South America reports concerning the fresh- water fauna are 

 perhaps most scanty of all. Frenzel, a German investigator, who lived 

 many years in Argentina, has published some interesting studies made 

 while there on the Protozoa; a few isolated notices of the lacustrine 

 fauna from various regions complete the list. 



From these statements it is apparent that the work done thus far 

 outside of Europe and North America is exceedingly limited, and that 

 for our judgment of the results in formal limnobiological investigations 



