DESULTORY SKETCHES IN NATURAL HISTORY. 47 



tion, and so of precluding the necessity of any tedious circumlocution 

 in rendering a specification of the exceptionable characters, even 

 although, considered in a physiological point of view, it may be of 

 trivial or unappreciable importance. From this actual want of 

 physiological importance may, indeed, sometimes arise the constancy 

 of such characters, which thus remain to indicate the obscured affi- 

 nities of aberrant species, or those which deviate in other respects 

 from the ordinary collective characters of their group, in conse- 

 quence of secondary modifications (to be explained presently) having 

 reference to some particular mode of life. 



There are numerous groups, however, of all degrees of value, 

 even the lowest assemblages of species, of which the integrity is 

 conspicuously manifest, and the definition easy. Such groups, no 

 matter how subordinate, may comprehend an immense number of 

 species ; and (to proceed now to the main difficulty of arriving at a 

 sound classification) these species may be variously modified upon 

 the same especial type, in adaptation to very different modes of life, 

 so that, on a cursory view, their mutual affinity may not be apparent, 

 the more especially as analogous modifications not unfrequently 

 occur of different types, the species exhibiting which display, in con- 

 sequence, much superficial resemblance, greater, of course, in pro- 

 portion as the minor types on which they are respectively organized 

 are more nearly allied together : thus, the analogous modifications 

 of two ordinal types of the same class resemble each other, of neces- 

 sity, more extensively than those of two different classes, &c. This 

 latter apparent, but unintrinsical, similitude, is distinguished by the 

 term analogy, as opposed to affinity. 



But few of those extraordinary species of animals, which, at first 

 sight, appear to be most widely removed from all others, are framed 

 on an especial sub-type, or cognizable subordinate model of con- 

 struction, of more than generic systematic value ; being simply mo- 

 difications of the same particular type on which certain other 

 animals are organized, the exclusive characters of which are trace- 

 able on analytical scrutiny. Thus, the Giraffe is essentially a mo- 

 dified Deer, with persistent horns ; the Flamingo a modified La- 

 mellirostral bird, or member of the Goose tribe, as intimated by its 

 whole anatomy, internal as well as external. Man himself displays 

 the same peculiar conformation as the three genera of Apes (Trog- 

 lodytes, Satyrus, and HylobatesJ,* but extensively modified for 



• These alone, of all the Anthropoid animals, have the liver divided as in 

 Man, a vermiform appendage to the coecum, a similar hyeid bone, &c. We 



