234 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



MADISON RIVER SYSTEM. 



Although large collections were made from streams of various sizes whose waters 

 find their way into the Missouri by way of the Madison, the only lakes so connected 

 upon which we worked were Mary Lake and Grebe Lake, the former draining through 

 Nez Perce Creek into the Firehole, and the other giving origin to the main branch of 

 the Gibbon. 



Mary Lake. This little lakelet, situated at a level of 8,200 feet, on the divide 

 between the waters of the Firehole and those of the Yellowstone, is an oval body of 

 water some 5 or C acres in extent, clear but shallow, with a fine gravelly beach 

 and very little vegetation. The immediate banks are rather steep, and the country 

 around is densely wooded with pine. The greatest depth at our visit was only 20 

 feet, and a lagoon-like bay near the lower end was but 5 or 6 feet deep. Both inlet 

 and outlet the former very small were dry, but the lake overflows into Nez Perce 

 Creek when the snow goes off in spring. 



Our collections from this lake were particularly remarkable for the great number 

 of one of the most beautiful and interesting of our fresh-water entomostraca, the 

 species known as Holopedium gibberum. In a haul made with the towing net at the 

 surface, in the shallow water near the outlet, a great quantity of this species was taken, 

 together with a still greater number of Diaptomm lintoni and an occasional Corethra 

 larva. The sun was shining at the time (11 a. m., August 14) and the water was 

 rippled by a light breeze. Near the bottom, at a depth of 16 feet, D. lintoni was the 

 prevailing form, mingled, however, with an almost equal quantity of Corethra larva; 

 and a considerable number of Daphnia schcedleri. 



The deeper bottom was of sandy mud, which contained a large number of Chi- 

 ronomus larvre in tubes most of them the common large red species a great number 

 of the common form of Pisidiwm, and many caseworms with tubes composed of sand 

 grains, several of them bicarinate. The dredge brought up a little Spongilla, several 

 of the usual annelids, and Corethra larvje, but no living vegetation. No amphipods 

 were taken from the lake, and no univalve mollusks. An unusual number of aquatic 

 insects occurred alongshore, most of them specimens of Agabus (two species) and 

 Deronectes griseostriatus. The leeches were, as usual, several species of Clepsine and 

 Nephelis maculata. 



Grebe Lake. This shallow, muddy lake, connected with the head waters of Gibbon 

 River, is so far secluded within the forest that it has no current name, and is locally 

 almost unknown. We reached it August 27, with saddle and pack animals, from the 

 Grand Canon Hotel, carrying canvas boat, seines, and our smaller apparatus. 



