178 TANYSIPTERA RIEDELI. 



new species by the process of natural selection — the struggle for existence 

 exerting in the case of natural selection a selective action." 



Now Agassiz says, " whenever a new, startling fact is brought to light 

 in science, people first declare it is not true, then it is contrary to religion, 

 lastly that everybody knew it before." 



Leaving out the two first, and making application of the last to the 

 Darwinian theory, something of it would appear to have been known to the 

 Greek chorus in ' Hecuba,' which Euripides causes to express itself thus : — 



" Sfitvo? ')(apaKTrjp, KaTrcaij/jio'i ev jSpOTol^ 

 iadXcHv yeveadai." 



But regarding the tails of our birds, remembering Comte's Law of 

 Philosophy, can a more simple hypothesis than sexual selection account for 

 the continual nibbles in question ? The class Aves, in the Animal Kingdom, 

 now almost in danger of being abolished * as a separate one at all, has no 

 doubt affinities with others. Take horses ; a crib-biter is one of the 

 commonest instances of the fidget, — which prevails amongst men also ; our 

 American cousins have invented the word " whittle " for a like process. 



Now, in order to be sure that sexual selection is the cause of these birds 

 picking out and destroying their tails, we must first satisfy ourselves that the 

 tail is improved thereby, and next that the birds themselves think so — two 

 rather difficult propositions ; for if we say the tail is more beautiful in its 

 spatulate form, this arbitrary declaration reminds one of the dogs' and horses' 

 tails mutilated by our ancestors (without natural or sexual selection certainly) 

 to improve the animals' appearance ! Nervous irritability appears to me a 

 more likely cause of this tail-picking ; but I by no means wish to be 



* Professor H. G. Seeley, F.G.S., in a lecture on "Fossil Forms of Flying Animals," thus 

 informs lis : — " That birds were descended from Pterodactyles in a direct line, he held to be highly 

 improbable. He thought they were one of those parallel lines of which we have so many in natui-e. 

 He did not think they became extinct because they were unfitted to live, nor that existing birds 

 were a higher group of animals or better adapted to the world in which they exist. This he 

 attributes to the changes iu the world's geology." — Morniny Post, October 13, 1875. 



