170 
IOWA ACADEMY OF SCIENCES 
PRELIMINARY NOTES ON THE IOWA ENTOMOSTRACA. 
BY L. S. ROSS. 
The careful work done by a few investigators has shown the 
relation existing between our common fresh water fish and the 
minute Crustacea of the streams and lakes. The results of 
these investigations prove the importance of the Entanostraca 
as a source of food supply for the young fry of many species, 
and even for the adults of some. The most extensive work 
upon this subject is that done by Dr. S. A. Forbes of the Uni- 
versity of Illinois. An account of the methods pursued and of 
the results obtained is given in the bulletins of the Illinois State 
Laboratory of Natural history; Bulletins Nos. 2, 3 and 6, and 
articles VII and VIII, Vol. II. 
Since the young fish depend for subsistence, to such an 
extent, upon the relative abundance or scarcity of the Entom- 
ostraca, it becomes a question not only of scientific interest, 
but of economic importance to learn concerning the distribution 
and abundance of the various species of this group of our fresh 
water fauna. The knowledge of the vertical distribution of 
different species in the lakes is of importance because some 
species of fish feed at one level and some at another. Some 
have their favorite haunts among the weeds of the shallows, 
others in the clearer, deeper waters. 
Consideration of these facts induced me to begin work upon 
the occurrence and distribution of Entomostraca in the state 
of Iowa. The paper presented is a report of work begun, 
rather than work completed. 
In order to combine pleasure with business, I decided to 
make a bicycle journey to the lake region of Iowa. In the first 
part of August of the past year, Mr. McCormack of Drake Uni- 
versity, and myself started across country en route for Lake 
Okoboji. We carried vials of alcohol and a coarse and a fine 
net; the latter being of bolting cloth. The streams did not 
