1 16 FOURTH REPORT — 1834. 



between theui. It is the object of the anatomist to investigate 

 the details of structure, and to record all facts connected with 

 the relative organization of animals. That of the zoologist is to 

 arrange these facts, and to make them subservient towards de- 

 termining the natural affinities of animals. Hence the latter is 

 but little concerned with any details Avhich do not exercise a 

 marked influence upon the manner of life, or with those minute 

 differences of structure which are not accompanied by corre- 

 sponding differences in the rest of the organization*. What he 

 seeks for is a subordination of characters, selected in the order 

 of their importance, on which to build his system ; and to judge 

 of the value of any one in particular which anatomy pi'esents to 

 him, he must trace by observation how far it is connected with 

 others, whether external or internal, or derived from the oecono- 

 my and mode of life, of which the value is knowTi. On such a 

 comparison, it may prove of too small importance to assist in 

 determining the affinities of a single species. Yet we can hardly 

 pronounce that it may not be found of some value hereafter ; 

 for although it may not in itself be sufficient to establish an affi- 

 nity, it may tend to cori'oborate our ideas respecting those which 

 M'ould seem already indicated by other characters. And con- 

 sidered in this view, even the minutest anatomical details may 

 prove of service to zoology. As an instance in point, we may 

 refer to Mr, Owen's recent discovery of a peculiar modification 

 of the stomach in the genus Semnopithecus\ . This genus had 

 been originally established by Geoffroy upon a slight difference 



* It has been a complaint with some natm-alists that zoologjf has of late 

 years been too much invaded by comparative anatomy, and that it has been in 

 danger of suflering from the encroachments of that allied science which was 

 originally called in to its assistance. i"or remarks on this subject the reader is 

 referred to the article Zoologie in the Diet. Class. d'Hist. Nat. (p. 727), and the 

 Introduction to the Hist. Nat. des Mammiferes, (p. 2, &c.) by M. Fred. Cuvier. 

 Mr. Swainson would also seem to say as much in \\\& Preliminary Discourse on 

 the Study of Nat. Hist. (pp. 84, 169, &c.), published since this Report was read. 

 To a certain extent there may perhaps be some ground for the complaint; but 

 it appears to me that it is only called for in those cases in which it has been 

 attempted to arrange animals solely from anatomical characters, no considera- 

 tion being paid either to external form or to the habits and manner of life. We 

 may fall into the error of attaching too much importance to differences of inter- 

 nal structure, as easily as we may in the case of those of external. The fact is, 

 the whole must be considered collectively, and it is the relative value of the or- 

 gans, when viewed in their mutual dependencies, which alone should decide 

 on which of them we are to base our system. But after having determined our 

 groups in this manner, we may generally succeed in finding, at least amongst 

 the higher animals, some external character by which they may be distin- 

 guished. And wherever this is the case, I fully agree with Mr. Swainson 

 (pp. 169 and 247), that for convenience sake such external characters should 

 be exclusively employed. 



f Zool. Trans., vol. i. p. 65. 



