11. 



ON THE OEIGm OF GENERA. 



Introduction. — The present fragmentary essay is a portion of 

 what other occupation has prevented the author from completing. 

 It does not, therefore, amount to a complete demonstration of the 

 points in question, but it is hoped that it may aid some in a classi- 

 fication of facts with a reference to their signification. When all 

 the vast array of facts in possession of the many more learned 

 than the writer are so arranged, a demonstration of the origin of 

 species may be looked for somewhere in the direction here at- 

 tempted to be followed. 



Conclusions of any kind will scarcely be reached, either by 

 anatomists who neglect specific and generic characters, or, secondly, 

 by systematists who in like manner neglect internal structure. 

 Such will never perceive the system of nature.* 



ANALYSIS OF THE SUBJECT. 



I. Relations of allied genera. 



First : in adult age. 



Second : in relation to their development. 



a. On exact parallelism. 



/8. On inexact or remote parallelism. 



y. On parallelism in higher groups. 



8. On the extent of parallelisms. 



II. Of retardation and acceleration in generic characters. 

 First : metamorphoses in adult age. 



a. The developmental relations of generic and specific char- 

 acters. 



* It might seem incredible that either class should systematize with confidence, 

 yet a justly esteemed author writes even at the present day, " However, there is 

 scarcely a systematist of the present day who does not pay m.ore or less attention to 

 anatomical characters, in establishing the higher groups!" (The italics are our 

 own.) As though a system were of any value which is not based on the whole struct- 

 ure^ and as though loxcer groups were only visible in external characters ; in a word, 

 as though external (muco-dermal, dental, etc.) characters were not " anatomical " ! 



