LIMNOLOGICAL OBSERVATIONS IN THE UPPER MISSISSIPPI. 399 
Table 23. — Composition of the plankton of the Mississippi River, and Lakes Pepin, Keokuk, and St. Croix. 
Cyanophycese: 
Merismopedia sp 
Clathrocystis seruginosa Henf . . . 
Microcystis sp 
flos-aquae (W) K 
Oscillatoria princeps V 
Lyngbya sp 
Anabfena flos-aqua; Br6b 
circinalis Rab 
spiroides K1 
spiroides ICC 
planktonica B 
Aphanizomenon flos-aquae R 
Bacillariaeeae: 
Melosira granulata (E) R 
spiralis E 
cremilata IC 
Cyclotella menenghiniana Br6b . 
Stephanodiscus niagarae E 
Synedra delicatissima W. S 
Fragilaria crotonensis K 
Navicula confervacea (IC) Gr 
Asterionella gracillima H 
Chlorophyceae: 
Desmidiumsp . . 
Closterium sp 
moniliferum E 
Staurastrum gracile R 
sp 
Cosmarium sp 
Spirogyrasp 
Actinastrum hantzchii Lag 
Scenedesmus quadricauda Brdb. 
acuminatus Ch 
minutus Ch 
sp 
Pediastrum duplex M 
simplex R 
Arcella vulgaris E 
sp 
Centropyxis aculeata St 
Difflugia pyriformis P 
corona W 
lebes P 
Mastigophora: 
Euglena ehrenbergii IC 
spirogyra E 
acus E 
Traclieiomonas shauinslandii L. 
Phacus longicaudus E 
Eudorina elegans E 
Platydorina caudata IC 
PHeodorina illinoisensis IC 
Volvox spermatosphara P 
Peridinium sp 
Ceratium hirundmella Sch 
Infusoria: 
Codonella lacustris E 
Stentor eoeruleus E 
Zoethamnium sp. (Adamsi S.) .. 
