160 BULLETIN OF THE BUREAU OF FISHERIES. 



PLANKTON. 



FOKMS. 



I 



A compiinitivoly siiiiiU amount of jjli^-toplankton was found in the lakes, and it 

 consisted cliii'tiyof diatoms, FnigiUtrla^ Axferlonclhi^ and Jfchixira. A .small portion 

 of it consisted of some colonies of a green alya, apparently a species of Profucoccas^ 

 and an occasional desmid, Stanrasti'inii . 



The following animal forms were found in the i)lankton oi the two lakes:" 



KoTU'-EHA. 



Annrea cochlearis Gosse. Triarthra Icini^iseta Ehrenlierg. 



Anurea aruleata Ehrenlierg. Pulyarthia fi|>. 



Nothiilca longispina Kellicott. Atriilamhna ?]i. 



Clil'EPODA. 



Diaptciiiius jiiilayi Mar^'h. Cyclops albidus Jurine. 



CyolopM pulchellus Koch. Cyclo])S viridis americanus Marsh. 



Cyclops .serrulatus Fischer. 



Cladocera. 



Daphnia byalina rieharili I'.urokhardt. Alona atiinis O. F. IMiiller. 



Latona sctifera O. F. MiiUer. .\loiia guttata Sars. 



Drepanothrix dentata Euren. Grajitoleberis testiidiiiaria Fischer. 



Eurycerciis lamellatus O. F. Miiller. Pleuroxas j)rocurvatus Ijirge. 



Camptoeercus reotirostris bi.serratus Schoedler. Cbydorus sphiericus O. F. Midler. 



Tlie following Cladocera were obtained from pooLs in the swampy meadow west 

 of Upper lake: 



Daphnia pulex De Geer. Eurycerciis lamellatiis (). F. Jliiller. 



Scapholeberis imicronata O. F. jMiiller. Camptoeercus rectirostris biserratus Sclioedler. 



Siinoeephalus vetulu.s O. F. Miiller. Pleuroxus procurvatus Birge. 

 Ceriodaphnia pnlchella Sars. 



Some plankton material was collected in a lakelet al)ove the town of Twin Lakes 

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

 (3,0.'J0 meters). The Cladocera were represented by Daplutia j>!t?r,i\ SliiiovejihaJus 

 retnJ us, PI, uriu'iix procurvatiiK:, and C/ujJoriin splia^rlens. 



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

 head of A\'iHis Gulch, a little southM'est of Twin Lakes, and has an altitude of about 

 rj,<)ti(» feet (;>,<ItiO meters). The water was found to he very cold, the banks of snow 

 w hich were the source of supitly being only a short distance awa}'. (riinuntn'us was 

 plentifid. and the Cladocera were represented by two forms, Mitct-othrix Jiirsuticornis 

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



C^UANTITY. 



Tile piaidctou ol>scrvations on the two lak(>s were few in luimber and consisted only 

 of veitical haids. In IWyi 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. \n IW?, three sets of catches were made on each lake. The observations 



" I am indebted to Dr. C. Dvvight Marsh for this list of Copepoda. The Diaptomus proved to be a 



new species and Dr. Marsh has recently described it. 



