6 



ON THE CETONIID.E OF SOUTH AFEICA. 



appear sometimes to be consonant with what we observe in nature. If we divide all animals 

 into sub-kingdoms, classes, orders, tribes, stirpes, families, genera, sub-genera, sections, sub- 

 sections, &c. &c. or any other names, we must not confound all these groupes together, but 

 during our investigations, preserve each of them in that proper subordination which may 

 have been agreed upon by naturalists. But here some one may observe that all groupes are 

 arbitrary and artificial, since after all they must depend on the selection and good pleasure 

 of man. To this I answer that affinities are natural ; and if all these affinities are expressed 

 by any mode of grouping, it follows also that the groupes must be natural; although, 

 certainly, these last must in some degree have depended on our selection. But in fact, 

 these groupes are only chosen because they coincide with the affinities which exist in nature. 

 Our grand object, when we are trying to find out a natural arrangement, is not to give 

 an arbitrary value to particular characters ; but to express all the relations, whether of affinity 

 or analogy, which may exist in the branch of natural history we study. If these relations are 

 all indicated by the arrangement, our object is gained ,• and it can be no objection whatever 

 to the system, that in our pursuance of an eclectic plan, a character which at one time we 

 set a value upon, is at another time esteemed of little worth. Indeed, it is obvious in every 

 part of natural history, that the most important characters break down in certain species, 

 and become at times perfectly worthless. Comparatively constant as is the structure of the 

 teeth in the genera of Mammalia generally, we find in some groupes, such as the Edentata, 

 or the genus Rhinoceros, that the dentition varies extensively in almost every species. Again, 

 in Botany, how steady is the dicotyledonous character of Exogenous plants j yet we have even 

 this most important distinction breaking down in certain famifies. One naturalist arranges 

 animals according to their brain and nervous system ; another tells us, he prefers their 

 osteology, and so on. Each point of structure, being of the utmost consequence to animal 

 economy, is concluded by its peculiar partisan to be therefore infallible as a ground of arrange- 

 ment. Very little experience, however, is sufficient to shew that each of these favorite hobbies 

 is unsafe to ride upon ; and we are in our search for an accurate way of expressing the relations 

 which connect various beings, obliged to adopt another plan of calculating the value of 

 principles of arrangement. 



My plan, as is well known, has ever been not to estimate the value of any arrangement 

 by the value in animal economy of the structure upon which this arrangement is founded, but 

 to make the importance of every organ or structure for purposes of arrangement, rise in inverse 

 proportion to its degree of variation. The consequence of this rule of procedure, has been 

 the birth of an arrangement which is universally applicable. And yet, even this rule is 

 nothing more than an abstract measure of the importance of some individual character in the 

 arrangement of that particular groupe, where we may happen to make use of it. It is a 

 rule, moreover, that we cannot always with safety put in practice ; for although with respect 

 to arrangement, it is ever an admirable instrument of correction, it is sometimes also a 

 dangerous one of discovery. Indeed, in discovering natural arrangement, we can never safely 

 swerve from the Linnean axiom, which although it alludes more immediately to ^' genera,^' 

 holds good equally of all groupes ; " Scias characterem non constituere genus sed genus 

 characterem, et characterem non esse ut genus fiat sed ut genus noscatur." We truly make 

 use of a process of tatonnement. We do not argue that such must be the groupe, because 

 such and such are, in our opinion, good and distinct characters ; but we say, such happens to 

 be the character, of no matter what importance, which prevails throughout the groupe, and 



