of elevated AIpi7ie Lahes. 279 



what thinner rods of the same length can be attached. Another 

 method is that which I have already described *, by means 

 of a float to which the net is attached by a cord of any desired 

 length, and with this one is able to fish a lake throughout its 

 whole extent. Upon this method is founded another kind of 

 investigation, by which we are enabled, loithout a boat, to 

 bring up from the middle of the lake, o.nd from exactly mea- 

 surable deytlis^ samples of mud with their inhabitants. Thus 

 a small float is drawn out upon the cord stretched over the 

 surface of the water, either to its middle or to any spot that may 

 be selected for examination. The cord is then drawn tightly to 

 both shores and fixed. The float has in the middle an aper- 

 ture somewhat larger than the transverse measurement of my 

 mud-scoop, which has already been described f- Over the 

 aperture a pulley is attached to an upright bar, and over this 

 runs a cord to which the apparatus is attached. When the 

 mud-scoop, which is lowered from the shore, has touched the 

 bottom it is drawn up again, and then the float with the appa- 

 ratus is pulled to one shore, a sufficient quantity of line being 

 let out at the opposite side. 



I now pass to a selection from the results obtained in 

 seventy- three freshwater basins elevated more than 600 metres 

 above the sea-level, commencing in the east of my field of 

 investigation. I have already reported upon the following 

 elevated lakes in Austria : — The Oftensee [^A^ metres), 

 Fuschlsee (G61), Krotensee (?), Vorderer Langbathsee (675), 

 Grundlsee (700), Altausseersee (709), Schwarzsee (720), Zel- 

 lersee (754), Vorderer Gosausee (909), and Plansee (977). 



In Upper Bavaria I investigated sixteen elevated lakes in 

 August and September 1884 and August 1885. Hitherto 

 only Leydig and Weismann have published contributions to 

 the knowledge of the vertical distribution of microscopic 

 organisms in this region, which is so rich in lakes, and these 

 relate to the Cladocera. My results as to the pelagic fauna 

 are as follows : — 



1. Stafpelsee, 601 metres.— (Protozoa :) Peridiuium, sp. ; Ceratium 



hirundiiulla , 0. F. Miill. (Kotatoria :) Anunfa intermedia, 

 Imh. (Cladocera :) DaplmeUa hrac]i}jura, Lidv. ; Daphnia, 

 2 sp. ; Bosmina, sp. ; Leptodora h>/aUna, Lillj. (Cope- 

 poda :) Cyclops, sp. ; Diaptomus, sp. 



2. KoHiGSEE, 603 metres. — (Prot.) Dinohryon diveryens, Imh.; 



Ceratium hirundinella, 0. F. Miill. ; Epistylis lacustris, 



* Zool. Anzeiger, no. 224. 



t Sitzimgsb. Akad. Wiss. Wieu, ]88o (April). 



