BLANCHES OF THE ANIMAL KINGDOM. 211 



It was not indeed by a lucky hit, nor by one of those 

 unexpected apparitions, which, like a revelation, suddenly 

 break upon us and render at once clear and comprehensible 

 what has been dark and almost inaccessible before, that I 

 came to understand the meaning of those divisions called 

 types, classes, orders, families, genera, and species, so long 

 admitted in Natural History as the basis of every system, 

 and yet so generally considered as mere artificial devices 

 to facilitate our studies. For years I had been labouring 

 under the impression that they are founded in nature, 

 before I succeeded in finding out upon what principle 

 they are really based. I soon perceived, however, that 

 the greatest obstacle in the way of ascertaining their true 

 significance lay in the discrepancies among different au- 

 thors in their use and application of these terms. Dif- 

 ferent naturalists do not call by the same name groups of 

 the same kind and the same extent : some call genera 

 what others call subgenera ; others call tribes, or even 

 families, what are called genera by others ; even the 

 names of tribe and family have been applied by some to 

 what others call sub-genera ; some have called families 

 what others have called orders ; some consider as orders 

 what others have considered as classes ; and there are 

 even genera of some authors which are considered as 

 classes by others. Finally, in the number and limitation 

 of these classes, as well as in the manner in which they 

 are grouped together under general heads, there is found 

 the same diversity of opinion. It is nevertheless possible, 

 that, under these manifold names, so differently applied, 

 groups may be designated which may be natural, even if 

 their true relation to one another have thus far escaped 

 our attention. 



It is already certain that most, if not all, investigators 



P 2 



