GLA8SIFIGATI0N. 439 



be considered as the same individual. He includes mon- 

 sters and varieties, not from their partial resemblance to 

 the parent-form, but because they are descended from it. 



As descent has universall}' been used in classing to- 

 gether the individuals of the same species, though the 

 males and females and larvee are sometimes extremely 

 different; and as it has been used in classing varieties 

 which have undergone a certain, and sometimes a consid- 

 erable amount of modification, may not this same element 

 of descent have been unconsciously used in grouping 

 species under genera, and genera under higher groups, all 

 under the so-called natural system? I believe it has been 

 unconsciously used; and thus only can I understand the 

 several rules and guides which have been followed by our 

 best systematists. As we have no written pedigrees, we 

 are forced to trace community of descent by resemblances 

 of any kind. Therefore, we choose those characters which 

 are the least likely to have been modified, in relation to 

 the conditions of life to which each species has been recently 

 exposed. Rudimentary structures on this view are as good 

 as, or even sometimes better than other parts of the organ- 

 ization. We care not how trifling a character may be — let 

 it be the mere inflection of the angle of the jaw, the manner 

 in which an insect's wing is folded, whether the skin be 

 covered by hair or feathers — if it prevail throughout many 

 and different species, especially those having very different 

 habits of life, it assumes high value; for we can account for 

 its presence in so many forms with such different habits, 

 only by inheritance from a common parent. We may err 

 in this respect in regard to single points of structure, but 

 when several characters, let them be ever so trifling, 

 concur throughout a large group of beings having different 

 habits, we may feel almost sure, on the theory of descent, 

 that these characters have been inherited from a common 

 ancestor; and we know that such aggregated characters 

 have especial value in classification. 



We can understand why a species or a group of species 

 may depart from its allien, in several of its most important 

 characteristics, and yet be safely classed with them. This 

 may be safely done, and is often done, as long as a suffi- 

 cient number of characters, let them be ever so unimpor- 

 tant, betrays the hidden bond of community of descent. 



