of elevated Alpine Lakes, 285 



Lastly, I have to add the results from two elevated Upper 

 Italian lakes, both situated near the Swiss borders : — 



1. Palxt (in the Val Maleneo, south of the Muretto Pass), 1993 



metres. — (Prot.) Ceratium hiruncUnella, 0. F. Miill. 

 (Rot.) Conochilus volvox, Ehr. ; Anitra:a longispina, Kelh 

 (Clad.) Lynceus, sp. (Cop.) Cyclops, sp. 



2. Tempesta (in the Val Brutto in passing towards Poschiavo, on the 



Piz Scalino), 2500 metres. — (Prot.) Dinohryon sertularia, 

 var. aJpinum, Imh. (Rot.) Anurcea longispina, Kell. 

 (Cop.) Cyclops, sji. ; Diaptomus, sp. 



General Results. 



The great majority of the freshwater basins investigated up 

 to 2000 metres elevation harbour a pelagic fauna very rich 

 in individuals. In some of the lakes situated at a still higher 

 level 1 also met with an enormous number of microscopic 

 animals, as, for example, in the lakes of the Bernina Pass : — 

 Nero, Bianco, Crocetta (^2307 metres). Still higher up the 

 result in this respect was surprising in the smaller water- 

 basins of the Upper Engadine : — Margum, Tscheppa, Sgris- 

 chus, and Furtschellas (2680 metres). In some of them a 

 Dophnia was particularly numerous, in others Diaptomus 

 alpinus was represented in remarkable numbers. 



From the tabular summaries drawn up we get the following 

 remarkable results : — 



Up to a height of 1796 metres (Silsersee) from seven to 

 sixteen species appear usually in each lake. The higher we 

 go up the smaller becomes the number of species inhabiting 

 the open water. 



As the most widely and generally distributed we find 

 representatives of the genera Daphnia^ Cyclops^ and Diap-' 

 tomus. The genus Bosmina occurred up to a height of 1908 

 metres (Cavloccio). Bythotrephes longimamis is wanting in 

 the lakes above 709 metres (Altausseersee). Leptodora hya- 

 lina occurs in almost all lakes up to 1075 metres (Spitzingsee). 

 Daplinella hrachyura is ascertained only up to a level of 780 

 metres (Schwansee). 



Among the Rotatoria the general distribution of Anurrea 

 loyigispitia^ which has already been noted, is to be mentioned 

 (highest lake, Sgrischus, 2640 metres). Pulyarthra platy- 

 ptera and Synchceta pectinata are met with here and there up 

 to considerable elevations, the former in the Materdell, 2500 

 metres, the latter in Crocetta, 2307 metres. Asplanchna 

 helvetica in nearly all lakes up to 774 metres (Alpsee, 



