11 OSTEOLOG-IA AVIUM. 



nature, and that a representative one to a certain extent, if not altogether — or, in other 

 words, that animals of one country have certain resemblances to those of another, and 

 take a similar situation in the animal ceconomy of their different habitats, but modified 

 to suit the peculiar circumstances under which they exist. I think, also, that a repre- 

 sentative system may be carried still further than this — viz. that the groups of one class 

 will to a certain extent represent those of another. 



Our present knowledge, however, is far too meagre for us to say with certainty this 

 or that is the arrangement that will suit the whole creation, or, in other words, is the 

 plan of the great Creator. 



I do not intend, therefore, to interfere with theoretical arrangements — they have done 

 much good in tempting naturalists to search out affinities and analogies, — but merely to 

 group those birds together which have a similarity of osteological organization. Affinity 

 and analogy are two words which have had given to them very many extraordinary 

 interpretations; but it is not my object to disturb them: whenever either word is used 

 in this work, it will be under the definition given to them by Professor Owen in his 

 Address to the British Association at Leeds*. 



It has long been a question whether animals found in a fossil state ought or ought 

 not to be admitted into an arrangement with existing ones. My own impression is, 

 that all animals are portions of one vast scheme of creation, and ought to be classed 

 together; for, as we can seldom say with absolute certainty where a group ends and 

 where it begins — let it be called class, family, subfamily, genus, or species, so nearly do 

 they in many particulars resemble each other, — so also with the connexion between 

 fossil and recent animals ; we cannot say precisely where those which have been con- 

 temporary with the present existing animals end and where they begin, or, in other 

 words, where any break existed between the two. For that break to be distinctly 

 marked, there- must have been a period in the world's history, since the creation, in 

 which no animal existed, and strata formed during it. 



In order to render this work intelligible to persons not previously acquainted with the 

 subject, it will be necessary to point out the names given by anatomists to the different 

 bones constituting the skeleton of Birds; these names refer to the representatives of 

 those bones in Mammalia from which their names are taken. The following references 

 to Plates I., II. and III. will show their position and names. 



The most difficult portion of the skeleton to understand is the head — the bones com- 

 posing it becoming anchylosed together in a very early stage of the animal's existence ; 

 the remaining bones can be made out with comparative ease. 



On account of this early anchylosis of the bones of the head, it is necessary, in order 

 to trace their boundaries, to employ that of a young bird ; the drawings relating to the 

 head, therefore, in Plates II. and III., are taken from that of a young Ostrich in my 

 possession : the head of the Ostrich has been before employed in most anatomical works 

 for the same purpose, on account of its size. 



* Professor Owen's Address to the British Association at Leeds, p. 18. 



