CLASSIFICATION 217 



serviceable in exhibiting tlie close .iffinitj between runii- 

 nauts and pachyderms. Robert Brown has strongly in- 

 sisted on the fact that the position of the rudimentary 

 florets is of the highest importance in the classification 

 of the grasses. 



Numerous instances could be given of characters 

 derived from parts which must be considered of very 

 trifling physiological importance, but which are univer- 

 sally admitted as highly serviceable in the definition of 

 whole groups. For instance, whether or not there is an 

 open passage from the nostrils to the mouth, the only 

 character, according to Owen, which absolutely distin- 

 guishes fishes and reptiles — the inflection of the angle of 

 the lower jaw in Marsupials — the manner in which the 

 wings of insects are folded — mere color in certain Algge — 

 mere pubescence on parts of the flower in grasses — the 

 nature of the dermal covering, as hair or feathers, in 

 the Vertebrata. If the Ornithorhynchus had been covered 

 with feathers instead of hair, this external and trifling 

 character would have been considered by naturalists as an 

 important aid in determining the degree of affinity of this 

 strauge creature to birds. 



The importance, for classification, of trifling char- 

 acters, mainly depends on their being correlated with 

 many other characters of more or less importance. The 

 value indeed of an aggregate of characters is very evi- 

 dent in natural history. Hence, as has often been re- 

 marked, a species may depart from its allies in several 

 characters, both of high physiological importance, and of 

 almost universal prevalence, and yet leave us in no doubt 

 where it should be ranked. Hence, also, it has been 

 found that a classification founded on any single char- 





