390 



The above facts recorded by different observers — and they are a 

 mere sample of what might be got together on this subject — serve 

 to show that there is a certain amount of variabihty in the phimage, 

 song, and nidification of our native birds. They are influenced 

 by circumstances ; they profit by their experiences ; they can learn 

 to do things differently from the way in which they did them 

 formerly ; they know how to turn to good account any accidental 

 advantage favourable to the purposes they have in view. 



To what extent all this may be carried, and whether the accumu- 

 lated results of small advances year by year towards an entire 

 change of character, of instincts and aptitudes, may not lead in 

 time to such a divergence as we now see, in so many cases, between 

 two closely allied forms thought to be distinct — this is a question 

 that must be left to be determined by local naturalists in different 

 parts of the country, when they shall have brought a much larger 

 number of facts and observations than we at pi-esent possess to 

 bear upon the points at issue. 



Let US now pass to the invertebrate division of the animal 

 kingdom. None of the classes of animals in this division offer a 

 more promising field for the considei'atiou of the Darwinian theories 

 than the class of insects. This arises from the circumstance of 

 the immense number of known species of insects, and the still 

 larger number probably which remain to be discovered, from the 

 great variety of forms which every order in the class exhibits, 

 and the remarkable changes which most of the species undergo 

 before arriving at maturity. In the larger families too, the species 

 are not only numerous, but often so variable and connected with 

 each other by such close affinities, that it is extremely difficult to 

 determine them at all, still more to group them into genera. 

 This is particularly the case with the Longicom Coleoptera, a 

 family of beetles containing 8000 species, in which variability 

 would seem to have attained its highest pitch. Mr. Bates remarks 

 that " if we except the two or three primary divisions of the 

 Longicorns, there is no portion of structure which retains a given 

 form throughout a number of species, sufficient to form a well- 

 defined genus of ordinary length or a group of genera." * 

 * See his Address to hint. Soc. Trans., 1868, p. Ixv. 



