INTRODUCTORY CHAPTER. 



Before entering upon a description of the group we propose to illustrate, it may not be 

 amiss to make a few observations on some of the divisions at present in use among Ornithologists, 

 more particularly Genera and Species, for we regard all other divisions, if indeed Genera are not 

 so, as certainly to a great extent arbitrary, and constituted merely for the convenience of the student 

 in Zoology, that he may at once turn to the required species or group he may wish to find, instead of, 

 as would be the case if he consulted the works of Buffon, having to turn over volumes before he 

 would be able to find the wished-for place. When we use the term arbitrary, as applied to divisions 

 of the animal kingdom, let them be called either classes, families, sub-families, or by any other 

 name, we mean, that in forming them there are generally rejected as many points of connection 

 between contiguous groups, and often stronger ones, than those made use of for their division. 

 Divisions and arrangements of some sort are, however, absolutely necessary for the Zoologist, under 

 each of which should be stated the points of connection it bears to others. Much has been said and 

 written on analogy and affinity, and the connection by one or the other of them between the groups 

 and species of the animal kingdom. We have not, however, been able to distinguish between them 

 in any other manner than that the former is generally applied when the groups or species between 

 which a connexion is supposed to exist are far removed from each other, and the latter when nearly 

 related, we shall use the terms indiscriminately, as convenient. 



A definition of species again presents to the Zoologist in particular another difficulty. 



The generally received opinion is that of John Hunter, viz. that hybrids between true species 

 will not be productive ; and this, we are inclined to believe, is partially correct, but not entirely so, 

 ae -ome birds, in a state of domestication, have bred together, and their offspring been productive, 

 although differing most materially in external form. 



It may be advanced, however, and with truth, that those animals upon which this experiment 

 has been tried have invariably been brought from countries far apart, and that consequently in a 

 wild state the experiment has never been tried ; no fact, that we are aware of, can be brought 

 forward towards an answer to this objection. Should it prove true, that animals inhabiting 

 different countries, and with slightly different forms and colouring, are of the same species, and we 

 confer there is good reason for supposing that this may be the case, it can only be accounted for 

 in this mode, namely, that at the universal distribution of animals after the Deluge, those of the same 



Species, and derived from the same parents, going to different localities, have in a succession ol ages 

 been influenced by various local circumstances, as climate, the plentitude, the want, or nature of food, 

 which causes have changed their form, colouring, and, in many instance's, their habits. 



We have DOthing whatever to urge against this theory, and we find much in favour of 

 it, considering the different varieties of the human form anil habits, although we cannot lor a 

 moment Suppose that they are derived from other thin the same common parents, and that the 



distinctions between the different races are caused otherwise than solelj by climate, yet do we make 



it 



