IOWA ACADEMY OP SCIENCE 
201 
some places the original vegetation has been supplanted by tame grasses ; 
in other places it remains undisturbed. The original vegetation consists 
of a dense growth of tall grasses and herbaceous forms. (Figs. 5 and 8.) 
Sivamps (Sloughs). The swamps are mostly devoid of trees and 
filled Avith a rank growth of grasses and sedges. The vegetation grows 
principally in clumps and on hummocks composed of roots and decaying 
vegetation. They are mostly uninfluenced by man, except as they are 
drained. (Fig. 5.) 
Shores of Lakes and Streams (Margmal forests). This habitat sup- 
ports the only natural timber in the region, and, Avhere undisturbed, 
there is ahvays a comparatively dense groAvth along the shores of the 
streams and larger lakes. The timber zones are, however, much narrower, 
and the trees more scrubby, than in the southern parts of the state. In 
most places at the present time this timber has been largely removed. 
(Fig. 6.) 
AQUATIC. 
The aquatic life is found in the lakes, ponds, sloughs and streams. The 
conditions in these habitats are very similar, as the lakes are for the most 
part shallow and the streams slow-flowing. (Figs. 9, 10, 11.) 
AFFINITIES OF THE FAUNA. 
loAAm is primarily a prairie state being situated well within the region 
of central North America that has long been noted for its rich growth 
of grasses and general lack of forest cover. With the exception of a 
small area in the northern part, the state lies entirely within the Caro- 
linian area, or eastern humid division of the Upper Austral Zone, of 
^lerriam. This area has been defined by MerrianT as follows : 
The Carolinau faunal area occupies the larger part of the Middle States, 
except the mountains, covering southeastern South Dakota, eastern Nebraska, 
Kansas, and part of Oklahoma; nearly the whole of Iowa, Missouri, Illinois, 
Indiana, Ohio, Maryland and Delaware; more than half of West Virginia, 
Kentucky, Tennessee, and New Jersey, and large areas in Alabama, Georgia, 
the Carolinas, Virginia, Pennsylvania, New York, Michigan, and southern 
Ontario. On the Atlantic coast it reaches from near the mouth of Chesapeake 
Bay to southern Connecticut, and sends narrow arms up the valleys of the Con- 
necticut and Hudson rivers. A little farther west another slender arm is sent 
northward, following the east shore of Lake Michigan nearly or quite to Grand- 
Traverse Bay. 
®Por detailed notes on the flora of the immediate region see : Macbride, T. H., Iowa 
Geological Survey, Vol. XL., pp. 499-508; Cratty, R. I., Iowa Geological Survey, Vol. 
XV, pp. 260-276; Pammal, L. H., The Iowa State Atlas (1904), p. 268. 
■^Merriam, C. Hart, Life Zones and Crop Zones of the United States. U. S. Dept. 
Agri., Bureau Biol. Surv., Bull. X, pp. 30-31. 
