AQUATIC INVERTEBRATE FAUNA OF WYOMING AND MONTANA. 
219 
On the west side a small permanent creek came in, about 30 feet wide and 2 feet 
deep at the time of our visit, with several acres of somewhat swampy ground at its 
mouth; and here also were three small warm creeks (150° F. ) and one of cold water 
(50°), the latter apparently supplied by melting snow from the borders of the Pitch- 
stone Plateau. A series of small lagoons, filled with sedge and bulrush, open into the 
lake along this shore. The cold waters from the Red Mountain range are diverted 
from this lake by the course of Aster Creek, which drains the northern slope and 
empties into Lewis River, about 2 miles below the lake. 
Treacherous and stormy weather during our brief stay prevented our making- 
many collections in the open water. The dredge was hauled, in fact, but once, and 
then at a depth of 56 feet, about a quarter of a mile above the outlet; and even the 
surface net was only twice used far enough from shore to give us the so-called pelagic 
entomostraca. The remaining collections were gathered inshore, in the swamp 
adjoining, and from streams, both warm and cool, on the western side. 
In the dredge, at 56 feet, with a bottom of fine black mud and dead vegetable 
debris, we took quantities of the large Oammarus , a few Allorchestes, many Chirono- 
mus larvae, specimens of Pisidium, and an undetermined annelid not preserved in 
condition for identification. The preponderance of Gammarm was as noticeable here 
as in the companion lake, although fewer were seen along shore in shallow water. The 
same may be said concerning the Diaptomi taken in open water in the surface net. 
The gigantic Diaptomus shoshone was relatively much less numerous, however, than 
the much smaller 1). sicilis var. It was feeding extensively upon pine pollen here, as 
in the other lake. Although properly pelagic forms — those most at home, that is, in 
the open water and in the deeper parts of the lake and found rarely, if at all, in the 
small lagoons — these Diaptomi nevertheless extend their range close inshore, where 
they might be seen with the naked eye in the water or taken in the net, even when 
the surface was decidedly rough. These collections contained many examples of a 
peculiar entomostracan (Holopedium gibberum) not noticed in Shoshone Lake, and also 
an abundance of a colonial rotifer belonging to the genus ConocMlus — allied to C. vol- 
vox, but apparently undescribed. * 
In the hike, near the entrance of the warm stream on the western side, were quanti- 
ties of young water-bugs (Notonecta), an occasional Corisa , Gammarm , Chironomus , and 
ephemeral larva*. Caseworms were also abundant in the lake, and the air alongshore 
was full of two species, one black and the other pale brown, just emerged and pairing. 
From a small lagoon filled with the overflow waters of a geyser, at the western side, 
we took with the hand net several specimens of Gammarm and hydrophilid larva*, a 
few Allorchestes dentata and young Corisa , many libellulid larvae, large and small, and 
larvae of Agrionincc, a single small Physa , and several water-beetles ( Ccelambus ). 
From a warm stream at the same place (150° F.) we have many ephemeral larvae, 
several caseworms and a single liydraclinid, a great quantity of large and vigorous 
specimens of Gammarm robustus , and a smaller number of Allorchestes dentata , many 
examples of Pisidium , a Physa , a few annelids ( Oligocholia), and a single leech 
{Nephelis 4-striata ) not taken by us before. The Gammarus was feeding very freely 
on dead and decaying vegetation and filamentous algae, with some fresh vegetable 
fragments and a little pine pollen. No traces of animal food occurred in two speci- 
mens dissected, one half-grown and the other of the largest size. 
Described on page 256 as C. leptopus, n. s. 
