IIl6 BULLETIN OF THE BUREAU OF FISHERIES. 



Determination of species. — When the fish have become habituated to his 

 presence the observer must, of course, learn to distinguish unerringly the species 

 which he is studying from other species with which it might be confused. 

 Workers who distinguish alcoholic fish at a glance may be puzzled to separate 

 species of living fish in the water. Here it is impossible to count scale rows, 

 pharyngeal teeth, or fin rays. On the other hand, the colors of the fish and their 

 mode of movement and the fact that species difficult to separate are not usually 

 associated make it comparatively easy to distinguish living fish in the water. 

 Yet the literature contains many instances of errors which have arisen from 

 the wrong determination of fish in their natural habitat. Safety lies in much 

 collecting and repeated comparison of the fish in the hand with that in the 

 water. After a time the observer of fish acquires something of the skill of the 

 field ornithologist, who recognizes by its method of flight the bird that is so 

 distant as to be a mere speck in the sky or by the wag of its tail or the tilt of 

 its head the one that is almost hidden in the bushes. So the ichthyologist finds 

 that living fish present characters that make their field determination easy and 

 that are not set down in the books. But he must discriminate, not only between 

 species, but between male, female, and young, and this is a much more difficult 

 matter. Lack of critical method in discriminating between the sexes has led 

 to very many errors recorded in the literature of the breeding habits of fishes. 

 Until very recently there was perpetuated the error that the female of the black 

 bass builds the nest and cares for the young, and a like error existed in respect 

 to the dogfish (Amia). 



Analysis of observations. — When the observer of fish habits has successfully 

 approached his subjects and has learned to distinguish between males, females, 

 and young, he is usually confronted by such a bewildering maze of behavior 

 that he sees but little clearly and is sorely tempted to patch out that little by con- 

 jecture as to the rest and to aid his patching by analogies drawn from other 

 groups of animals. There is here but one safe rule of procedure, familiar enough 

 in other fields of science, but too little applied in the field study of animal habits. 

 It is that the observer must proceed analytically; he must take one element of 

 the behavior at a time and study that until he can describe it accurately. What 

 is the precise position of the male and female in a pair of spawning fish? To 

 answer this question accurately the observer must ask himself many others. 

 What is the position in each fish separately? In each sex, what is the position 

 of the tail, the head, the dorsal fin, the anal fin, the pectoral fin, the pelvic fin? 

 Each of these questions must be answered by a separate observation, many 

 times repeated, and only when they have been answered and the answers put 

 together does one know the position of the two sexes in the spawning pair. 

 Only by securing answers to innumerable and apparently unimportant questions, 

 only by constant " Fragestellung " does one make progress in the field study of 



