48 
IOWA ACADEMY OF SCIENCES. 
truth in the remark made by another botanist, with a sniff, 
that you might as well try to classify wall paper. The diffi- 
culty, however, is not greater than in other orders of equal size. 
At first it might appear that the state of Iowa, with its 
monotonous rolling prairies would offer little diversity of 
aquatic plant life, but this has not proved to be the case. For 
present purposes the various localities where diatoms are 
found may be grouped in four divisions. 
First . — Creeks and rivers, with the bogs and old river chan- 
nels connected with them. 
Second. — Springs, with the bogs and ditches watered by 
them. 
Third . — The lakes found in that portion of the state covered 
by the Wisconsin drift. 
Fourth . — Fossil deposits. 
The first localities named, the creeks and rivers, were the 
first from which material was collected. Here abound the 
smaller naviculse, synedrse, melosirse, and most abundant of 
them all, the gomphonemsB, which may be seen as long, gela- 
tinous streamers of a rich brown color, in moving water, or as 
a covering on the stones in rapids and cataracts. In the 
brooks and ditches the more fragile forms of nitzschia and 
synedra are found. Under favorable conditions these little 
organisms cover the bottom of the brooks and ditches to a 
depth sufficient to color everything a rich brown. When the 
sun shines on them the oxygen liberated raises them to the 
surface of the water and they are carried along until they 
strike a twig or board or other obstacle, where they may be 
seen at times an iuch in depth and several square feet in 
extent. 
East of Iowa City, about two and one- half miles, there is a 
prairie slough, having in it at one point a broad and shallow 
basin, where the water stands a greater portion of the year. 
In the month of June this presents, to the diatomist at least, a 
most remarkable appearance. In this basin, covering an 
extent of about an acre, and to the depth of eight or twelve 
inches, is a fiocculent seal brown mass of living diatoms. Here 
Fragillaria virescens stretches its tiny ribbons, and Meridion 
intermedium spreads its miniature fans in numbers innumerable. 
In the northern portion of the state, where the rivers are 
but little more than motionless lagoons, the amount of aquatic 
material is indeed prodigious. In such quantities do alga©, 
