116 PHILOSOPHY OF ZOOLOGY. 



extended wings, is not always the same, in the individuals 

 of the same species. But the outline of the wing, where all 

 the feathers are at full growth, and the shape of the fea- 

 thers, especially the primaries, furnish characters which may 

 be confided in. The more specific the purpose of any organ y 

 or any part of an organ, the fewer variations take place in 

 the forms which are exhibited. 



It is a matter of regret, that hitherto so little attention 

 has been paid to the characters furnished by the shape, in 

 the descriptions of animals which have been drawn up. 

 The task is not a difficult one; and the nomenclature, 

 usually derived from well known forms tp which definite 

 terms are affixed, is of easy application. 



The naturalists who exclusively employ, in the classifi- 

 cation of animals, the marks furnished by the external cha- 

 racters, usually take some notice of the places to which ani- 

 mals resort, denominated the Station, or Habitat. 



The examination of this character can only be carried on 

 successfully in the natural haunts of the species. In those 

 places, the instincts of their nature are exhibited in action ; 

 and we can trace the motions which are executed, and the 

 ends which these are destined to accomplish. When cir- 

 cumstances do not permit us to conduct this examination 

 in the situations which animals ordinarily frequent, we form 

 what is termed a MENAGE ; and endeavour, in a confined 

 state, to study those manners, which, in a wild state, were 

 precluded from our observation. The aquatic animals are 

 the most difficult to preserve in a living state ; they have, 

 consequently, presented so many obstacles to an examination 

 of their manners, that naturalists remain comparatively ig- 

 norant of their history. 



The terms which are usually employed to express the 

 relations of the different parts of the animal frame, are sel- 

 dom so much restricted in their signification as to prevent 



