PREFACE 



Several years ago the method of procedure in the laboratory work in verte- 

 brate zoology in this University was changed from the type plan, then in common 

 use, to the comparative plan. No doubt a similar change has been made in 

 many other institutions. A suitable manual for the comparative method has, 

 however, hitherto been lacking; the present publication attempts to supply this 

 need. There can scarcely be any question of the superiority of the comparative 

 method of study of vertebrate anatomy, for by this method the student not 

 only learns all of the anatomical facts brought out by the type method but he 

 also acquires an understanding of vertebrate and human structure which he is 

 quite unable to attain by the older method of study. In view of the fact that 

 the majority of the students taking courses in vertebrate anatomy at the present 

 time are preparing for medicine, it seems obligatory that they be taught the 

 "history of the human body" as revealed by the study of the anatomy of verte- 

 brates. On the other hand, the comparative method is perhaps faulty in that 

 it may not give the student a clear-cut picture of the characteristics of the 

 various classes of vertebrates. Thus, while the student readily learns the history 

 of the aortic arches, for example, he does not readily associate any particular 

 group of vertebrates with a particular condition of the arches, when the com- 

 parative method is followed. This defect should probably be remedied in the 

 lecture part of the course. I have attempted to remedy it to a slight extent by 

 introducing the section on the general features of typical chordates. 



In this manual I have attempted not only to give the laboratory directions 

 for the dissection of the various systems, but I have also presented in connection 

 with each system a very brief, generalized, and simplified account of the develop- 

 ment and evolution of that system. It has seemed to me essential that such an 

 account precede or accompany the laboratory directions in order to give a signifi- 

 cance to the facts revealed by the dissection at the time when the student 

 becomes aware of those facts. As the consultation of other texts during a dissec- 

 tion is inconvenient and time-consuming, I have thought it the most practical 

 plan to include such explanatory matter in the laboratory manual. Simple 

 illustrations have been added to clarify further the explanations. I have not, 

 however, in the least intended that these explanations should take the place of 

 reading in the standard texts of comparative anatomy. The students should 

 understand that additional outside reading is expected of them. 



In making such brief and generalized explanations as are given here it is 

 impossible to take into account numerous exceptions and variations. I must 

 therefore ask the indulgence of the expert in vertebrate anatomy for the omission 

 of qualifying clauses in the explanatory accounts of the various systems; in 



