388 Bemarks on the Principles on which 



subordinate forms; that is to say, forms characteristic of 

 smaller groups, distinct from one another, but marked by 

 characters of far less importance than those common to all 

 of them. Such, among others, are those of Botaurus and 

 ^ycticorax Steph. ; which, accordingly, may well deserve to 

 rank as subgenera : but surely it is against all principle to 

 retain ^4'rdea, Botaurus, A 7 ycticorax, Ciconia, &c, as so many 

 distinct genera in the family of ^rdeidae, thereby leading to 

 the inference that the two middle groups are of the same 

 value and importance as the first and last.* 



The above cases are sufficient to illustrate the subject I am 

 considering. To multiply examples is unnecessary. It is no 

 part of my object to point out, in every instance, what groups 

 are to be ranked as genera, and what as subgenera, or even to 

 offer any definition of the term genus f, with the hope of 

 reconciling the various opinions that have been given on this 

 point. I merely wish to remind naturalists of those princi- 

 ples which must be the basis of a natural classification ; and 

 to observe, that, whatever value of meaning they may attach 

 to the word genus, it is most unphilosophical to designate alike 

 by that title two or more allied groups, of which the values 

 are manifestly not the same. 



It may be observed, indeed, that, acknowledging the prin- 

 ciple in question, we may still err, oftentimes unavoidably, in 

 attaching its proper value to any new group that presents 

 itself. To determine this with exactness, presupposes our 

 knowledge of all the other existing groups belonging to the 

 same family. For the value of a group depends on the 

 value of its characters; and although, in general, in the 

 higher groups especially, we judge of characters d priori, 

 that is to say, from their importance, considered in them- 

 selves, and not with reference to the number of species in 

 which they may be found present, yet there are cases, in 

 which their value may be in some measure modified by con- 

 siderations of this nature. Thus, if we were to find a single 

 species assuming a particular character apparently of no 

 great importance in itself, we might regard such character 

 as indicating a specific peculiarity, but should hardly 

 look upon it in any higher light. If, however, it was 

 discovered afterwards that the same character belonged to a 

 considerable number of species, especially if those species 

 offered among themselves a general resemblance in their 



* See Shaw's Zoology y continued by Mr. Stephens, vol. ii. part 2. 



•j- I must beg, however, to decline adopting one lately given, which is so 

 indefinitely worded as to be almost applicable to any natural group, of 

 whatever value. See Entomological Magazine, No. iii. p. 298. 



