AQUATIC INVERTEBRATE FAUNA OF WYOMING AND MONTANA. 235 



Our' collections were made with a surface net in deep and sballow water, with a 

 dredge at a depth of 36 feet (the greatest found), and with the hand net from grass 

 and lily pads near the margin, from the gravelly bottom in shallow water, and from 

 weedy mud this list exhausting, in fact, all the varieties of situation offered. 



The lake lies north and south in greatest length, the outlet leaving the south end 

 and flowing to the south at first. It is in some respects a duplicate of Mary Lake, 

 but is somewhat larger, being half to three-quarters of a mile long and about two- 

 thirds as wide. It is of oval form, with grassy margins, commonly sod to the water's 

 edge, rimmed round with lily pads and other water weeds, and with a bottom of soft, 

 black mud. The banks were somewhat swampy, but the ground was higher to the 

 north and west. Three small streams now into the lake, one from the northeast and 

 two from the west. 



Although so unlike Shoshone Lake, its assemblage of animal forms bore a striking 

 resemblance to that of the larger, clearer lake. The absence of fish, the abundance 

 of Oammarus and D-iaptomi, and the scarcity of Daphniida; are examples. On the 

 other hand, the grassy borders and weedy shallows entertained a much greater abun- 

 dance and variety of insect forms than the hard and bare margins of either Shosho ie 

 or Mary Lake. 



In the mud of the bottom were many large red Ghironomus larvae, a few speci- 

 mens of Gammarus, and the usual Pixidium. The entomostraca were mostly Dinpto- 

 mus lintoni, which replaced in this small lakelet the J). shoxhone of the other lake; here 

 also we found Daphnia clathrata, n. s., the only locality thus far discovered for it. It 

 was not abundant in Grebe Lake, and may have bred primarily in the swamps adjoin- 

 ing. A species of Cyclops also occurred here in small numbers, which is described on 

 page 248 as C. capllliferus. 



Inshore collections were unusually fruitful. Q-ammarus and Allorclic'stc.i were very 

 abundant along the margin in the weeds and grass, and Pisidium especially was 

 extraordinarily common. Here also were agrionitie and ephemerid larva}, caseworms 

 with cases of fine sand, Corim, Piaidium, Phym, Chironomns, and Flpongilla, and on 

 the mud among grass and algra were dytiscid and small sialid larv;e, Phi/so, and Pisid- 

 ium, Nephelis and Glepxine, Allorchestes and Gammarus, Ghironomus and ephemerid 

 larvae, larvse of dragon-flies, and specimens of Haliplus. 



This lake was an additional illustration of the fact that, in this high mountain 

 region, where aquatic life seems oppressed with unusual difficulties, change in cir- 

 cumstance takes extraordinary effect, so that each lake has its distinct and special 

 zoological character. 



