238 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



tentbs of the product of every deep-water haul with the surface net. Diaptomus, the 

 text ommouest form in Yellowstone Lake, was not certainly seen at all in Flatliead, 

 but was replaced by a new variety of Episvhura (E. nevadensis, var. Columbia-), which 

 held practically the same relation to Daphnia.thorata which I), sicilis held to D. pulcx 

 in the other lake. Besides these most abundant pelagic forms we found only occasional 

 examples of Lcptodora, Cyclops,* Bosmina, Soafholeberis, and Sida cryntallina, the 

 last two shore forms which probably would- not have been taken very far out. Be- 

 tween the deeper waters and the weedy northern margin of the northeast bay is an 

 extensive flat of sand, under from 5 to 15 feet of water, and here our tow-net hauls 

 were always remarkably unproductive. Partly, perhaps, because of the barrier offered 

 by this barren belt of shallow water, the pelagic Crustacea did not appear at all in 

 our alongshore collections as they did in Yellowstone Lake. The assemblage of forms 

 brought out by the small amount of work inshore which we had time to do, was in 

 no way remarkable, unless for its deficiencies. Gammarus and Allorchentes dentata 

 among the amphipod crustaceans, Sida, Eurycercus, and Cyclops gyrln-u* among the 

 entomostraca, species of Physa, LimiHta, and Planorbis among mollusks, and the usual 

 miscellany of hydrachnids, epliemerid and Ghironomus larvae, larvse and adults of 

 Dytiscidfc and llydrophilida;, Corisa, planarians, leeches, and annelids among the 

 latter, Pristina lacustris were the commoner kinds. 



Our first dredging in Flatliead Lake was made about 200 yards from land, off the 

 month of a small cove with bluffy shores the first below the Helena Club House 

 in water ranging from 76 to 125 feet. The dredge came up, after a haul of .about a 

 quarter of a mile, well filled with soft mud, mostly of slaty color, but somewhat 

 streaked with reddish brown and mixed with a considerable debris of particles of 

 dead wood, fragments of dead leaves, cast skins of insect larvae, and the like. 



The greater part of the zoological product of this haul was a mass of the cusne 

 ciuin of a species of polyzoan (Plumatetta, near arethusa), and with these came Chi- 

 ronomus larvte, red and pale, a dozen specimens of Pixidium, a few cyprids, and a 

 number of undetermined, slender, pale-red, annelid worms, 2 to 3 inches long and a 

 millimeter in diameter. 



The second dredging was made in the same vicinity, but a little below the pre- 

 ceding and farther out. Beginning about half a mile out from the head of the same 

 cove, at a depth of 125 feet, we hauled nearly a mile to south and west, taking up the 

 dredge at a depth of 153 feet, when about three-fourths of a mile from the point form- 

 ing the southern limit of the cove. This haul yielded precisely the same product as 

 the other an abundance of the same species in approximately the same ratios. 



Neither in variety nor quantity was the animal life of the deeper waters of this 

 lake, as shown by our work with the dredge and towing net, at all in advance of Yel 

 lowstoue Lake, with the single exception of the polyzoan of our dredgings, and this 

 was possibly only a local accident. 



The bottom and margins of the southern end of the lake seemed comparatively 

 barren, the weeds washed ashore containing, in fact, scarcely anything but Allor- 

 chesten dentata, dytiscid and epliemerid larvae, and Corisa. From the stony flat at 

 the outlet a considerable supply of caseworms of several species was obtained, Corisa, 



* Mostly a species undescribed, allied to thomasi of the Great Lakes, but differing in its more 

 slender, more loosely articulated form and in the armavure of some of its legs. 



