Biological Survey — Erie-Niagara Watershed 



77 



other peculiarities make each species easily distinguishable sub- 

 sequently, but counting the vertebrae offers the best original guide. 

 This information together with knowledge of the fish fauna of the 

 locality permits us to narrow down the possibilities and very often 

 to spot the species immediately. In some small specimens strong 

 light is sufficient to reveal the spinal column, but usually it is 

 necessary to use stain and in larger fishes to bisect. Every stage 

 was described in detail, and it is hoped that eventually a series 

 of keys for the identification of all lake fishes at different stages 

 may be published. 



The adult fish is usually so different in coloration, body pro- 

 portions, and general characters from the very young that exist- 

 ing adult descriptions are of no assistance in work of this kind. 



Helgoland young fish trawl 



It seemed wise to attempt a collection of postlarvae and young 

 adults Avhich might form a connecting link between the tiny speci- 

 mens caught in our nets and the older known adults. The Stream 

 Survey staff* gave valuable co-operation, bringing in 37 species 



* I am indebted also to Dr. John Van Oosten for a very large and complete series 

 of young whitefish; E. L. Wickliff for whitefish eggs and young, pike perch, herring, 

 and yellow perch; J. L. Hart for whitefish, herring, perch, pike perch, and muskalonge; 

 J. P. Snyder for herring, whitefish, lake trout, black bass, and brook trout; Dr. 

 Emmeline Moore for muskalonge eggs and larvae; Miss Ida Mellen for brook trout 

 eggs; F. B. Voegele for whitefish and lake trout eggs; and A. P. Miller for muskalonge 

 larvae. Mr. Vernon S. L. Pate made the drawings for this report. Miss Elizabeth 

 L. Saunders was general laboratory aide. 



