DEVILS LAKE, KORTH DAKOTA. 17 



The water at Devils Lake was found to vary from 1.0054 to 1.009; 

 according to locality. Detached bodies, like Mission Lake, especially 

 when surrounded by developed lands, were, for obvious reasons, found 

 to possess the higher densities. The lowest, 1.0054, was observed in 

 Mission Bay, and is to be accounted for by the seepage of small quan- 

 tities of fresh water from Court or Spring Lake. The average den- 

 sity of the main portion of the lake was 1.006. 



BIOLOGICAL FEATURES. 



The fauna and flora of Devils Lake are found to have an impor- 

 tant bearing on the subject of the present investigation, and demand 

 consideration at this point. Collections were made of the life of the 

 lake, both zoological and botanical, including the plankton, and notes 

 were gathered on all facts relating to the cause of the paucity of fish. 



But two varieties of fishes were found, a stickleback {Eucalia in- 

 constans) and a minnow {Pimephales promelas)^ which were ob- 

 tained in abundance, both in frequent hauls of the seine and by a 

 crude but effective trap constructed by one of the party. They were 

 taken literally by the hundreds and without use of bait in any way. 

 The sticklebacks were generally large in size and of a uniform black 

 color, though specimens of a lighter color and mottled appearance 

 were numerous. Often many were seen swimming close to the sur-. 

 face, and, possessing but little activity, were easily captured by hand^ 

 while they were seen to be caught by the thousands by gulls and terns. 

 A good proportion of the minnows secured bear nuptial tubercles^ 

 with brighter dashes of color ; the heads and lateral bands were black. 



Prior to 1889 Devils Lake teemed with pickerel, probably Esox 

 lucius. Observations upon their abundance and size and the cause 

 of their disappearance are reserved for special mention. 



The batrachians were represented by two species, the hellbender 

 (Cryptohranchus alleghaiiiensis) and the leopard frog {Rana pi- 

 jnens). Both were abundant, the former constituting the principal 

 food of the cormorants. In this connection it may be stated that on 

 visiting the " Rock Pile," a small rocky island in the main section 

 of the lake, used as a rookery by cormorants and a few white peli- 

 cans, the food disgorged by frightened birds was found to be com- 

 posed entirely of sticklebacks and young hellbenders. One of these 

 food piles contained 18 and 13 of these animals, respectively, the hell- 

 benders all under 3^ inches in length. Fully 100 nests and 500 birds 

 were counted on this island. Leopard frogs were everywhere abun- 

 dant along the shores. No turtles are known to occur in the lake. 



Muskrats are occasionally seen, and bird life was well represented. 

 During the investigations in this region over fifty species of birds 

 were listed. Immense flocks of black-headed or laughing gulls 



