THE LIFE OF DEVILS LAKE 55 



quate to maintain a constant level. Like other shallow lakes its 

 temperature in summer probably reaches a maximum of 30° C. 



It has a high salt concentration, as shown in the analysis 

 (table 3), with a correspondingly high osmotic pressure. 



Its inhabitants, so far as studied, are similar to those of Main 

 Lake. 



LAKE C 



Lake C is about 0.3 sq. km. in extent with a maximum depth 

 of 1.8 m. It was separated from what is now East Lake, about 

 1885. It lies in a shallow draw between two morainic ridges, and 

 is probably spring fed, having apparently maintained its present 

 level for some time. 



In spite of its constancy of level, it shows a considerable con- 

 centration of dissolved solids as indicated by the analysis (table 3). 



The study of Lake C has not been thoro enough to admit of 

 any very definite comparison between its life and that of other 

 lakes in the complex. In general this appears to be much less 

 abundant both in species and individuals than that of neighboring 

 ponds. A striking feature is the apparent absence of Nodularia, 

 which is so characteristic of the more alkaline lakes of the complex. 

 The same absence is noticeable in Spring Lake and Lakes N, and 

 P. The reason thereof is not obvious. Where comparatively few 

 collections have been examined, as is the case with these lakes, it 

 would not be safe to be too emphatic in making negative conclusions. 

 A sufficient examination has, however, been made to reveal Nodu- 

 laria were it common, as it is in the principal lakes of the complex, 

 so that its absence is probably significant, tho of what, cannot at 

 present be said. The salt content of lake C is rather low, about the 

 same in amount and proportion as that of Main Lake in 1907. In 

 1909 Nodularia was observed as one of the most characteristic species 

 in Main Lake. The other lakes, with the possible exception of Lake 

 P, are all shallow, N and being but temporary pools, and rang- 

 ing in different seasons from nearly fresh to exceedingly alkaline 

 ponds or mud flats. This may explain the absence of Nodularia 

 in them, but no satisfactory explanation is at present evident for 

 Lake C. 



SPRING LAKE (pl. 9). 



This is little more than a mud flat covered by a third to a 

 half a metre of water. Were it not for a supply from springs it 

 would undoubtedly have long since been dry. It has been separated 

 from the main body for about 40 years. 



In winter it freezes solid, while in summer it reaches a temper- 

 ature of about 30°. 



