BEHAVIOR AGREEMENT AMONG ANIMALS. 



307 



less of the trials. All the other species were among the stones, 

 either on or under as indicated in the diagram. 



BOTTOM 



HYDROPSYCHE OR RAPIDS COMMUNITY 



70 80 90 100 



ETHEOSTOMA 



CAMBARUS 



GONIOBASIS 



HYDROPSYCHE 



ARGIA 



PERLA 



HEPTAGENINAE 



PSEPHENUS 



SAND-GRAVa BOTTOM OR POOL COMMUNITY 

 10 20 30 40 50 60 70 80 90 100 



10 20 30 40 



32 



50 60 



70 80 90 100 



SAND-GRAVEL BOTTOM BREEDER 



SAND-GRAVEL BOTTOM BREEDER 



SAND-GRAVEL BOTTOM BREEDER 



33 



SAND 



j AMONG STONES 

 MUD 



34 



ON STONES 



NOTROPIS 



HYBOPSIS 



AMBLOPLITES 



CALOPTERYX 



CAMPELOMA 



MACROMIA 



ANODONTUIDES 



SPHAERIUM 



NOTROPIS 



HYBOPSIS 



AMBLOPLITES 



CALOPTERYX 



CAMPECOMft 



MACROMIA 



ANODONTOIDE? 



m 



j| SPHAERIUM 



ROCK SAND 



TTT;T| UNDER STONES 

 BURROWING 



HARD BOTTOM ^H 

 NEGATIVE TO STONES 



FIGS. 31-34. Show the reactions to hard vs. sand bottom and to loose stonet> 

 vs. wax bottom in per cent, of total. Fig. 31 shows the per cent, of rapids animals 

 on sand and hard bottom, a large preference for the latter being evident. In the 

 case of the pool fishes results of the experiments were unsatisfactory and as further 

 tests had to be abandoned on account of cold weather the data of Forbes and 

 Richardson ('08) is included to indicate what the probable results of experimenta- 

 tion will be. It will be noted that the preference is quite generally for sand, rock 

 and mud occupying a much smaller portion than sand. Fig. 33 shows the relation 

 to rocks on a. wax bottom. Negative reaction to rocks is small. A striking agree- 

 ment is shown in the general preference for stones. Fig. 34 shows the relation of 

 the animals of the pool community to sand bottom with reference to burrowing. 

 Here again the breeding data of the fish is taken from literature to indicate what 

 might be found experimentally. Experiments performed at 14 C. 



Fig. 34 shows further probable relations of the pool animals 

 in such bottom experiments. The fishes usually bury their eggs 

 and other species excepting Calopteryx bury the body in the 

 sand. 



