On the present slate of Zoology. 27 



then, by combining- afterwards the results obtained separately in this 

 manner, we may one day be in a position to form some judgment of 

 the true natural system. But, before selecting our particular field of 

 observation, it is very desirable tbat we take, as far as possible, a ge- 

 neral view of the whole subject. This is requisite, in order that we 

 may get some idea of that uniformity of plan which pervades more 

 or less the entire animal kingdom, and of that complicated chain of 

 affinities by which its several divisions are held together. Hardly 

 any group is circumscribed by such absolute boundaries, as to admit 

 of being viewed correctly, except in connection with all others to 

 which it bears any kind of relation. It may not be necessary to study 

 these others in detail, but without some knowledge of them, we shall 

 hardly prosecute successfully our own department. Except we have 

 some acquaintance with other structures, we shall hardly set a right 

 value upon those modifications of structure which come before us ; 

 and except we see something of the affinities of other animals, we 

 shall hardly arrange according to their true relations those with which 

 we are concerned. We shall especially overlook those approaches to 

 the organization of contiguous groups by which is effected a passage 

 from one to another, and those partial resemblances, or relations of 

 analogy, which may be so often (some think always) traced between 

 corresponding parts of two parallel series. 



With respect to the particular groups, which, in the present state 

 of the science, call most loudly for the attention of naturalists, we 

 can only make a few remarks, supplementary to those which we have 

 already made elsewhere.* We would observe, generally, that it is 

 towards the bottom of the system that their exertions are most want- 

 ed. We as yet know but little of the classification of the Invertebrate 

 animals, below the Mollusca and Annulosa. We may think that we 

 can, with some appearance of truth, point out the leading divisions, 

 or even proceed to the arrangement of the more subordinate groups ; 

 but every day is bringing to light some fresh discoveries calculated to 

 make us mistrust those views which are founded more upon a priori 

 reasoning than upon actual observation. We are so in ignorance of 

 the real structure of certain families ; we find others established upon 

 characters of general resemblance, but offering internally such diffe- 

 rences of organization ; — that we can hardly say at present, with re- 

 ference to these animals, on what systems of organs we can most re- 

 ly as the basis of a natural classification, or indeed, in many instances, 

 what organs are present. It is a question of dispute at this moment, 



* Report on Zoology, p. 249. 



