338 VICTOR E. SHELFORD. 



ences in dissolved content in the water, doing so without regard 

 to the specific peculiarities of their behavior, such as methods 

 of moving their tails, mouths or opercles. By way of further 

 illustration, we note that, according to the accounts of naturalists, 

 there are striking resemblances between the behavior of some of 

 the antelopes of the savannas of Africa and certain of the sa- 

 vanna kangaroos of Australia. In other words certain kangaroos 

 are ecologically similar to some antelopes. As has already been 

 stated, the zoologist is usually unduly impressed with specificities 

 such as mode of movement of limbs, body, etc. Now if my 

 reader pictures an African antelope running gracefully from a 

 pack of Cape hunting dogs (Selous, pp. 119-123) and an old-man- 

 kangaroo leaping from a pack of dingoes (Ward, '07, pp. 41 , 243) 

 noting mainly the specific peculiarities of the movement of limbs 

 and body of the pursued in each case, he will be dwelling upon 

 specificities of little ecological significance and missing the point 

 of mew of the ecologist altogether. These specificities of behavior 

 are matters of little ecological significance; it matters not if one 

 animal progresses by sommersaults so long as the two are in 

 agreement in the matter of reactions to physical factors as indicated 

 by the manner of spending the day, 1 avoidance of forests, swamps, 

 cold mountain tops, etc., entirely available to them, and in the 

 mode of meeting enemies as indicated by the reaction to the 

 approaching enemy a relation to other animals of the com- 

 munity. As a further example, the specific method of avoiding 

 stimuli shown by Paramoscium is not a matter of any considerable 

 ecological importance. The chief argument against ecological 

 classification is based upon specificity of behavior. With all the 

 marked specificities there can be no similarities! Let us apply 

 this logic to a few particular cases. Since there are specific 

 differences in the behavior of different fish species, different fish 

 species do not turn back from carbon dioxide in a similar way 

 and are not similarly affected by it ! Since there are species and 

 no two species of a genus are alike there can be no genera; since 

 there are genera each with definite characters, there can be no 

 families, etc. Specificity of behavior comes in ecological classi- 

 fication or other ecological consideration as a matter of tertiary 



1 Lydekker, III., 243; Vol. II., p. 322; Riverside, N. H., Vol. V., pp. 36-37. 



