160 BULLETIN OF THE BUREAU OF FISHERIES. 



PLANKTON. 

 FOKMS. 



A comparatively small amount of phytoplanktou was found in the lakes, and it 

 consisted chiefly of diatoms, Fragilaria, Asterionella, and Melosira. A small portion 

 of it consisted of some colonies of a green alga, apparently a species of Protococcus, 

 and an occasional desmid, Staurastrum . 



The following animal forms were found in the plankton of the two lakes:" 



Rotifera. 



Anurea cochlearis Gosse. Triarthra longiseta Ehrenberg. 



Anurea aculeata Ehrenberg. Polyarthra sp. 



Notholea longispina Kellicott. Asplanchna sp. 



Copepoda. 



Diaptonius judayi Marsh. Cyclops albidus .Turine. 



Cyclops pulchellus Koch. Cyclops viridis americanus Marsh. 



Cyclops serrulatus Fischer. 



Cladocera. 



Daphnia hyalina richardi Burckhardt. Alona affinis O. F. Miiller. 



Latona setifera O. F. Miiller. Alona guttata Sars. 



Drepanothrix dentata Euren. Graptoleberis testudinaria Fischer. 



Eurycercus lamellatus O. F. Miiller. Pleuroxus procurvatus Birge. 



Camptocercus rectirostria hiserratus Schoedler. Chydorus sphrericus O. F. Miiller. 



The following Cladocera were obtained from pools in the swampy meadow west 

 of Upper lake: 



Daphnia pulex De Geer. Eurycercus lamellatus O. F. Miiller. 



Scapholeberis mucronata O. F. Miiller. Camptoceicus rectirostris biserratus Schoedler. 



Si cephalus vetulus 0. F. Miiller. Pleuroxus procurvatus Birge. 



Ceriodaphnia pulchella Sars. 



Some plankton material was collected in a lakelet above the town of Twin Lakes 

 on Mount Elbert. This small body of water has an altitude of about 10,000 feet 

 (3,050 meters). The Cladocera were represented by Daphnia pvlex, Simocephalus 

 r, fiilux, /'/, iiro.rns procurvatits, and Chydorus sphsericus. 



Some material was obtained also from Willis Lake, which is situated near the 

 head of Willis Gulch, a little southwest of Twin Lakes, and has an altitude of about 

 12,000 feet (3,660 meters). The water was found to be very cold, the banks of snow 

 which were the source of supply being only a short distance away. Gammarus was 

 plentiful, and the Cladocera were represented by two forms, Macrothrix hirsuticornis 

 Norman & Brady and Eurycercus lamellatus O. F. Miiller. 



QTJANTITT. 



The plankton observations on the two lakes were few in number and consisted only 

 of vertical hauls. In 1902 the observations on Upper Lake consisted of two series of 

 catches in July and four in August. A single set of catches was made in Lower Lake 

 in August. In 1903 three sets of catches were made on each lake. The observations 



o I am indebted to Dr. ('. Dwight Marsh for this list of Copepoda. The Diapiomm proved to be a 

 new species and I>r. Marsh has recently described it. 



