296 



VICTOR E. SHELFORD. 



Argia pulrida 



Perla sp 



Heptageninae Shores large lake=. 



Psephenus Shores large lakes. 





FIGS. 1-8. General form of rapids animals. Drawn on the same scale; all 

 about natural size; seen from the side slightly above, i, the rainbow darter 

 (Etheostoma coeruleum Raf.); 2, crayfish (juvenile) (Cambarus virilis Hag.); 3, 

 snail (Goniobasis livescens Mke.); 4, caddis worm (Hydropsyche); 5, damsel fly 

 nymph (Argia sp.}; 6, stone fly nymph (Perla sp.); 7, mayfly nymph (Hepta- 

 8, water penny (Psephenus sp.). 



POOL COMMUNITY. 



The fishes live in the open water or in the shade of the scattered vegetation. 

 Calopteryx rests on the vegetation. The rest burrow in the bottom. The species 

 studied were not selected carefully as representative but were merely collected 

 from pools. 



Species, Usual Habitat 

 Sand-bottomed Pools, 



Occasionally on or in 



Rarely in 



Nolropis alherinoides Raf Mud bottom Lakes and ponds (Forbes 



and Richardson '08). 



Hybopsis kentuckiensis Raf Mud bottom Lakes and ponds. 



Ambloplites rupestris Raf Large streams. 



Calopteryx sp 



Campeloma subsolidum Ant Mud bottom Among vegetation. 



Anodontoides ferussacianus Lea.. Lakes 



Sphaerium slrialinum (?) Lake Mich, (n meters). 



Side views of each of the animals (Figs. 1-16) studied show the 

 radically different ways in which the animals receive stimuli 

 such as current, horizontal light, etc. 



