Chap. XIV.] CLASSIFICATION. 207 



same organ, as we have every reason to suppose, has 

 nearly the same physiological value, its classificatory 

 value is widely different. No naturalist can have 

 worked long at any group without being struck with 

 this fact ; and it has been fully acknowledged in the 

 writings of almost every author. It will suffice to 

 quote the highest authority, Eobert Brown, who, in 

 speaking of certain organs in the Proteaceoe, says their 

 generic importance, " like that of all their parts, not 

 only in this, but, as I apprehend, in every natural 

 family, is very unequal, and in some cases seems to be 

 entirely lost." Again, in another work he says, the 

 genera of the Connaracese " differ in having one or more 

 ovaria, in the existence or absence of albumen, in the 

 imbricate or valvular sestivation. Any one of these 

 characters singly is frequently of more than generic 

 importance, though here even when all taken together 

 they appear insufficient to separate Cnestis from 

 Connarus." To give an example amongst insects : in 

 one great division of the Hymenoptera, the antennae, as 

 Westwood has remarked, are most constant in structure ; 

 in another division they differ much, and the differences 

 are of quite subordinate value in classification ; yet no 

 one will say that the antennae in these two divisions of 

 the same order are of unequal physiological importance. 

 Any number of instances could be given of the vary- 

 ing importance for classification of the same important 

 organ within the same group of beings. 



Again, no one will say that rudimentary or atrophied 

 organs are of high physiological or vital importance ; 

 5"et, undoubtedly, organs in this condition are often of 

 much value in classification. No one will dispute that 

 the rudimentary teeth in the upper jaws of young 



