vi PREFACE, 



tary lesson book, and on the other to make its contents too 

 scanty. It would of course be easy indefinitely to add to the 

 details herein stated regarding the structure of the animals 

 referred to. Some readers, no doubt, will expect greater 

 detail ; and I can hardly hope, in this first essay, not to have 

 overlooked points it might have been desirable to bring 

 forward. 



Others may be disposed to think that too large a portion 

 of the book is devoted to the consideration of the skeleton 

 only. 



This predominance has, however, been deliberately assigned 

 to the osseous structures for the following reasons : I. The 

 general resemblance borne by the skeleton to the external 

 form ; 2. The close connexion between the arrangement of 

 the skeleton and that of the nervous system, muscles, and 

 vessels ; 3. The relations borne by the skeleton . of each 

 animal to the actions it performs, i.e. to the mode of life and 

 habits of the various animals ; 4. The obvious utility of the 

 skeleton in classification and the interpretation of affinity ; 

 5. Parts of the skeleton, or casts of such, are all we possess 

 of a vast number of animals formerly existing in the world, 

 but now entirely extinct ; a good knowledge of the skeleton 

 must therefore be of great utility to those interested in 

 Palaeontology. 



Moreover, it is a recognized maxim with teachers of (exclu- 

 sively) human anatomy that a thorough knowledge of the 

 bones is not only a necessary preliminary to other anato- 

 mical knowledge, but that the latter is acquired with com- 

 parative ease when the first has been well mastered. I have 

 deemed it advisable to act on this maxim in teaching the 

 anatomy generally of man and of the animals herein 

 referred to. 



