102 
BULLETIN OF THE BUREAU OF FISHERIES. 
was found, most commonly above the thermocline. A few Polyarthra platyptera 
were found above 12 m. Notholca longispina was about evenly distributed in very 
small numbers throughout the lake. 
Aphanocapsa was the predominant alga. 
Cyclotella was the only diatom found in the lake. 
LAKE SAMMAMISH, WASH. 
The Crustacea in this lake were largely crowded into the 0-3 m. stratum, 
where there were 52,000 individuals per cubic meter of water. This number 
decreased very rapidly to only 9,000 between 3 and 6 m. In the upper stratum 
of the lake there were 60.5 per cent of the Epischura nevadensis, 35 per cent of the 
Cyclops bicuspidatus, 74.8 per cent of the Diaphanosoma leuchtenbergianum, and 
42.9 per cent of the Bosmina obtusirostris. 
The maximum number of nauplii per cubic meter of water was found in the 
region of the thermocline, or between 9 and 12 m. 
The majority of the rotifers were Mastigocerca, while 25.1 per cent were 
Notholca longispina and 16.7 per cent were Polyarthra platyptera. The maximum 
number per cubic meter of water was found in the 0-3 m. stratum. There was a 
slight decrease in numbers in the stratum between 6 and 9 m. Fifty per cent of 
the Polyarthra, 42.8 per cent of the Mastigocerca, and one-third of the Notholca 
were above 3 m. 
Diatoms were present in considerable numbers at all depths. The maximum 
number per cubic meter of water of other algae, such as Staurastrum, Microcystis, 
Aphanocapsa, and Anabsena, was in the 0-3 m. stratum of the lake. 
SILVER LAKE, WASH. 
The vertical distribution of the Crustacea was quite uniform, with the maxi- 
mum number per cubic meter of water just below the thermocline, or between 
5 and 10 m. All of the Epischura nevadensis var. columbise were in the 0-5 m. 
stratum of the lake. Daphnia longispina var. Jiyalina and Diaphanosoma leuchten- 
bergianum were both above 10 m. Sixty per cent of Cyclops bicuspidatus was 
between 5 and 10 m., but none was found above 5 m. 
The maximum number of nauplii per cubic meter of water was noted at the 
bottom of the lake, between 10 and 14 m. Over three-fifths of the nauplii were 
found in this stratum. The rotifers were rather evenly distributed throughout 
the lake, with the maximum number per cubic meter of water between 10 and 
14 m. Almost one-half of Polyarthra platyptera, slightly over half of Anursea 
cochlearis, and almost one-third of Notholca longispina were found in this stratum 
of the lake. Conochilus and Mastigocerca were in the surface stratum. 
Ceratium was found in small numbers above 10 m. 
The algse were not very numerous for a lake of this depth. They occurred in 
largest numbers between 5 and 10 m. Anabsena was found in small numbers 
above 10 m. 
Fragilaria and Asterionella were the only diatoms found. The maximum 
number per cubic meter of water was in the 0-5 m. stratum. None was found 
below 10 m. 
