68 MIMICRY AND HOMOPLASY 



known cases of plumage resemblances amongst 

 birds and to the longitudinal striping of some 

 mammals, e.g., young wild pig, young tapir, 

 mouse-deer, striped squirrels, etc. In all these 

 cases convergence is independent of selection. 



In order to guard against conveying a wrong 

 impression, it may be well to add that in cases 

 of double or multiple convergence such as are 

 mentioned on p. 52, there is no a priori pre- 

 sumption of correlation between the several 

 characters which are repeated in the different 

 types. Thus there is no correlation between 

 the separately moving eyes of Hippocampus and 

 its prehensile tail, because other Lophobranchiate 

 fishes (Pipe-fishes), which have a straight tail, roll 

 their eyes in the same way, as can be seen very 

 prettily in the Naples Aquarium. The property 

 which these fishes present in common with 

 chameleons is the possession of exceptionally 

 sluggish habits ; and the extreme mobility of 

 the eyes compensates for the relative inflexibility 

 of the body. Nor is there any correlation 

 between the oviposition of the Platypus (Ornitho- 

 rhynchus] and the shape of its bill ; the latter is 

 correlated with its aquatic and feeding habits. 

 The conjunction of characters may be a coin- 

 cidence ; the repetition of the coincidence is an 

 act of convergence. 1 



1 For a discussion of correlation between teeth and limbs in 

 the evolution of Mammalia see Professor H. F. Osborn's paper 

 on "The Law of Adaptive Radiation," American Naturalist^ 

 vol. xxxvi., 1902, pp. 353-363. 



