440 



The Ohio Journal of Science [Vol. XIX, No. 8, 



There were two well defined instances of distribution being 

 influenced by unlike food habits at different ages. One of these 

 was shown by Physa which exhibited a very clear stratification 

 and the other case was the relation of nymphal Notonecta and 

 algse. In this instance, however, there was no stratification. 



TABLE 6. 



Group 



Species 



Station 



Coleoptera 

 Adults 



Coleoptera 

 Larvae 



Diptera Larvae 



Hydroporus mixtus 



Hydroporus concinnus. . . . 

 Tropisternus nimbatus. . . 

 Philhydrus ochraceus. . . . 



Dineutes assimilis 



Agabus disintegratus 



Coelambus laccophilinus. 

 Gyrinus aquiris 



Dytiscidae 



Gyrinidae 



Hydrophilidae. 



Haliplidae 



Lagriidae 



Corethra sp 



Metriocnemus sp . 

 Chironomus sp.. . 

 Tanypus sp 



Ephemeridae 

 Nymphs 



Tricoptera 



Hemiptera 



Sialididae 



Arachnida 



Heptagenia variabiis 



Amelitus sp 



Caenis allecta 



Ephemerella excurcians. 



Leptocerid larva. 

 Hydrospyche sp.' 



Notonecta insula ta. 



Corisa 



Gerris conformis. . . 



Sialid larva. 



Limnochares aquaticus. 

 Pirata fibriculosa 



Crustacea 



Asellus attenuatus. . 



Cyclops sp 



Nauplius (Cyclops). 

 Cypris sp 



MoUusca 



Annelida 



Vertebrata 



Physa heterostropha . 



Eggs of Physa 



Lymnaea humilis 



Planorbis parvus 



Glossiphonia stagnalis . 



Sandpiper. 



Total number of species . 



26 



17 



10 



11 



