LIMNOLOGICAL OBSERVATIONS IN THE UPPER MISSISSIPPI. 
351 
ager, Mississippi River Power Co., for information concerning the hydrography of 
the river and of Lake Keokuk; and to Dr. H. C. Frankenfield, United States Weather 
Bureau, who kindly furnished the data on river stages; and to express his indebt- 
edness to Prof. T. H. Morgan, head of the department of zoology in Columbia Uni- 
versity, for the courtesy of extending him the privileges of the laboratory where the 
examination of the plankton was made. 
The author also wishes to make acknowledgment for valuable assistance in 
examination of plankton to Dr. Albert Mann, Smithsonian Institution, for identifi- 
cation of the diatoms in some samples of the collections; to H. K. Harring, United 
States Bureau of Standards, for his advice in identifying some of the species of 
Rotifera; to Dr. C. C. Curtis, Columbia University, for identifying the water plants 
collected in Lake Pepin and Lake Keokuk; and to Dr. T. E. Hazen, Barnard College, 
for identifying the blue-green algae collected in St. Croix Lake. 
METHOD OF INVESTIGATION. 
SCHEDULE OF LOCALITIES. 
It is very important in a comparative investigation to have the collections 
obtained and the observations made simultaneously, but as only one person was 
working in this case this was impossible. The first observations were made on July 
1 1 at Fairport (fig. 3) , where the headquarters of the expedition had been established. 
Lake Keokuk was visited twice, in June and at the end of September, the investi- 
gation of Lake Pepin was continued from August 18 until September 10, and the 
various parts of the river were visited during the periods August 1-18, September 1-5, 
and September 10-20. The details of this schedule are given in the following table: 
Table 1. — Schedule of investigation of Mississippi River between Hastings, Minn., and Alexandria, Mo., 
in the summer of 1921 . . 
Distance 
from St. 
Paul by- 
steam- 
boat 
channel, 
in miles. 
July. 
August. 
Points visited. 
Distance 
from St. 
Paul by 
steam- 
boat 
in miles. 
July. 
Alexandria, Mo 
Des Moines River, Iowa. . 
Lake Keokuk between 
Keokuk, Iowa, and 
Burlington, Iowa 
Burlington, Iowa 
New Boston, 111 
Fairport, Iowa 
Rock River, 111 
Rock Islands Rapids, 
near Davenport, Iowa. . 
Six miles above Clinton, 
Iowa 
Four miles below Belle- 
vue, Iowa 
One mile below Cassville, 
Wis 
Turky River, Iowa 
Wisconsin River, Wis 
Prairie du Chien, Wis 
One mile below Lansing, 
484r442 
441f 
411§ 
3824 
237f 
233J 
211J 
2071 
15-30 
14 
13 
11-12 
Between De Soto, Wis., 
and Lansing, Iowa 
Root River, Minn 
La Crosse, Wis 
Between Winona and 
Homer, Minn 
Zumbro River, Minn 
One mile above W abasha, 
Minn 
Reads Landing, Minn 
Lake Pepin between 
Reads Landing and the 
head of the lake 
Above the head of Lake 
Pepin 
One mile above Red 
Wing, Minn 
Diamond Bluff, Wis 
St. Croix River and Lake, 
Wis 
Prescott, Wis 
Between Prescott, Wis., 
and Hastings, Minn 
77| 
771-55 
54J 
49 
401 
