The Productivity of Fish Food in Oneida Lake 185 



a few species have a wide distribution in relation to depth, 

 the trichopterid Molanna and the dipterid group Tanypinse 

 alone extend from shallow water to the deepest areas exam- 

 ined (ij/2 and 2 to 18 feet). These two orders have the 

 greatest number of species and genera with a wide range in 

 bathymetrical distribution. 



Relation to Age and Season. Enough data arc not at 

 hand with which to discuss the relation of the associated ani- 

 mals to age and season. Some of the groups (as Diptera, 

 some Crustacea) have many generations in a year while others 

 have but one or two and in a few cases (Sialis) two years 

 may be required to reach maturity. Many groups have periods 

 of development and emergence, as the caddis-flies and May- 

 flies, both of which had reached their maximum period before 

 the writer began his field work (July) in 1916. Many of the 

 associated animals dififer from the Mollusca in passing through 

 one or more stages in their development and the two groups 

 are not, therefore, comparable in respect to their presence in 

 season or their condition as regards age. The knowledge con- 

 cerning the length of time required for attaining adult life 

 and the number of generations in a year of the associated 

 animals forming the food of fish is indispensable in com- 

 puting the available amount of fish food in any body of water. 



Annotated List of Species 



This list includes only those species and groups collected in 

 the field work of 1916. In a number of groups (Oligochseta, 

 Ephemerida, Trichoptera, Diptera) it has not been possible 

 to make identifications to species, and in several cases below 

 the family, owing to the present lack of knowledge concern- 

 ing the larval stages of these groups. Rearing of these larval 

 stages is the only means for unquestionable determination of 

 them. The species here listed do not include all that inhabit 

 this region, but only those that were collected arbitrarily by 

 means of the unit area system. Systematic search for any 

 single group would undoubtedly result in finding many addi- 

 tional species. The absence of Protozoa, Rhizopoda, and 

 Infusoria from the list does not mean that these groups do 



