476 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
examples of Pisidium adamsi a single Gammarm fasciatus (doubtless taken in lift- 
ing the dredge), and one dead shell of Planorbis campanulatus. 
Finally, two hauls of the trawl and two of the dredge in the middle of the lake, at a 
depth of 23 fathoms, yielded quantities of the softest black mud with some admixture 
of dead leaves, an abundance of large red Chironomus larvae, Pisidium adamsi, and 
the undetermined worm {Limnodrilus) already mentioned. The only other specimens 
secured by this deep-water work (which aggregated over a mile of continuous hauling) 
were two specimens of Bphmnum, one of Valvata tricarinata, one of V. sincera, a dead 
Physa, a few pupae of CoretJira, and three leeches. No living vegetation was found 
here except diatoms. 
With the surface net, in open water, I secured at this time only a moderate num- 
ber of a Daphnia closely resembling D. retrocurva Forbes (and possibly a varietj' of 
that species), a few examples of Epischura lacustris Forbes, a Diaptomus (apparently 
a variety of sicilis), another large copepod, Limnocalanus macrurus, and the remark- 
able cladoceran form, Leptodora hyalina. 
The material of 1887 was obtained mostly with a towing net, in eighteen collec- 
tions, made at various points along the margin in shallow water and also in the deep- 
est parts of the lake. The following lists, although not exhaustive, are sufficiently 
complete to show the dominant and associate species, and the conditions governing 
their relative abundance. 
DEEP-WATER COLLECTIONS, 1887. 
Upper end of lake, August 6, deep water, clear weather, sunrise, wind. A surface haul and a 
small collection, with much small vegetable drift. 
1. Larvm of Chironomus. 
2. Young neuropterous larvae. 
3. A large hydrachnid, undetermined. 
4. Allorohestes deniata Faxon. A few females bearing eggs. 
5. Daphnia retrocurva, var. An occasional specimen. 
6. DaphneUa brachyura. 
7. Sida crysiallina. 
8. Cyclops, sp. 
9. Epischura lacustris Several specimens 
August 5, deep water, at surface, sunset, calm. A small collection, obtained by dragging the 
towing net behind a steamer. 
1. Daphnia retrocurva, var. A few specimens. 
2. Epischura lacustris. The principal part of the collection. 
August 5, deep water, 10 a. m., at surface, cloudy, calm. A small collection. 
1. Chironomus. A few examples of larv® and pupae. 
2. Daphnia retrocurva, var. The greater part of the collection. 
3. Epischura lacustris. Several specimens. 
4. Diaptomus sicilis, var. A few examples. * 
August 9, deep water (20 fathoms), 10 a. m., sunshine, net hauled about 10 feet below surface. A 
large collection. 
1. Leptodora hyalina. Several specimens. 
2. Daphnia retrocurva, ^a,v. The greater part of the collection. 
3. DaphneUa h) achyura. A few examples. 
4. Cyclops, sp. A few examples. 
5. Epischura lacustris. A few examples. 
6. Diaptomus sicilis and var. A few. 
