124 Barriers to Dispersion of River Fishes 
to any existing barriers between the river and the Great Lakes. 
In northern Indiana the watershed is often swampy, and in 
many places large ponds exist in the early spring. 
At times of heavy rains many species will move through con- 
siderable distances by means of temporary ponds and brooks. 
Fishes that have thus emigrated often reach places ordinarily 
inaccessible, and people finding them in such localities often 
imagine that they have ‘‘rained down.”’ Once, near Indian- 
apolis, after a heavy shower, I found in a furrow in a corn-field 
a small pike,* some half a mile from the creek in which he 
should belong. The fish was swimming along in a temporary 
brook, apparently wholly unconscious that he was not in his 
native stream. Migratory fishes, which ascend smallstreams to 
spawn, are especially likely to be transferred in this way. By 
some such means any of the watersheds in Ohio, Indiana, or 
Illinois may be passed. 
Fie. 78.—Creekfish or Chub-sucker, Hrimyzon sucetta (Lacépéde). Nipisink 
Lake, Illinois. Family Catostomide. 
It is certain that the limits of Lake Erie and Lake Michigan 
were once more extended than now. It is reasonably prob- 
able that some of the territory now drained by the Wabash 
and the Illinois was once covered by the waters of Lake Michi- 
gan. The ciscot of Lake Tippecanoe, Lake Geneva, and the 
lakes of the Oconomowoc chain is evidently a modified de- 
scendant of the so-called lake herring.{ Its origin most likely 
* Esox vermiculatus Le Sueur. t+ Argyrosomus sisco Jordan. 
t Argyrosomus artedi Le Sueur. 
