xxii INTRODUCTION. 



During the dissection of any animal it is always advisable 

 to have the skeleton at hand for reference, and at some time 

 or other a systematic study should be made of it. It is for 

 this reason that an account of the skeleton is prefixed to the 

 directions for the dissection of each type. 



With slight variations the management of the work is the 

 same for all the subjects selected. The external characters 

 are first studied : then a rough dissection is made for the 

 purpose of acquainting the student with the position and 

 general relations of the chief organs ; at the conclusion of 

 this stage the brain is removed and preserved for future 

 examination ; finally, the various parts are studied more or 

 less in detail. The student should try and arrange his work 

 so as to get the brain removed on the first day. 



In the case of the Lamprey and the Lizard, which can be 

 satisfactorily preserved whole in alcohol, it has not been 

 thought necessary to remove the brain until it is wanted for 

 dissection. 



The directions for each stage in the dissection are given 

 in " indented " paragraphs numbered with Roman numerals ; 

 the following ordinary paragraphs with Arabic numerals 

 giving descriptions of the structures brought into view by 

 such dissection. By this arrangement the work is divided 

 into sections, many of which may be omitted without serious 

 disadvantage, if time runs short. The paragraphs in small 

 type may also be omitted by the beginner. 



When a dissection is prolonged over say two days, the 

 subject should be placed, when not in use, in a preservative 



