116 



IOWA ACADEMY OF SCIENCE 



Vi)L. XXVI. 19i:t 



surprised the author to find Boleosoma in water as quiet, shallow 

 and warm as that just above the backwater. While seining the 

 backwater a large snapping turtle {Chclydra serpentine L.) was 

 caught. This may have accounted in part for the absence of any 

 great number of fish in the pool. At any rate, the results of seining 

 the pool showed a dirth of specimens compared to what was found 

 in the spring-fed pools above. This pool would have served as an 

 excellent duck pond for the adjacent farm, but if it should be so 

 used care should be taken to remove any other turtles which may be 

 there. 



Below the dam, the stream is very small and insignificant. Ap- 

 parently there is less water flowing here than in the stretch be- 

 tween the springs and the backwater above the dam. The stretch 



Fig. 15. — Dam built near head of Dry Hun to form pond evidently to furnish 

 drinking water for stock. 



of sand may account for this, as some of the water may go below 

 the surface and appear again elsewhere. Certainly so far as va- 

 riety of habitats and of bottom and species are concerned the region 

 from here to the north end of the "Diagonal Road" is very uninter- 

 esting. The bottom is uniformly composed of soft black mud which 

 probably prevents the water from entering lower strata of earth 

 freely. Three small tributaries in the upper stretches of this area 

 scarcely augment the size of the stream, they are so small. The 

 graph shows that all of the species reported for the stream with 

 the exception of Notropis and Boleosoma are reported from this 

 area. What few pools appear are pools because of their increased 

 width rather than because of increased depth and do not furnish 



