PREFACE xi 



Compliance with the above requests might seem to be limiting 

 the individual initiative of the student, and putting class emphasis 

 upon the middle group of students rather than the selected few. 

 The defense for this is: (1) the belief that the interested and 

 brilliant student will discover enough for himself to stimulate 

 his imagination; (2) the pragmatic statement that the average 

 student goes to professional school with little idea as to the 

 bearing of comparative anatomy upon human structures; and 

 (3) the fact that this method has proved its efficiency with our 

 students at New York University. 



Although most scientific terms are defined when first used, a 

 glossary is appended for convenience. In it both the derivations 

 of the words and their definitions are given. A second appendix 

 gives a more complete classification of the vertebrates than is 

 included in the body of the text. A generic name which is used 

 in the text will be found defined in the glossary. Then by refer- 

 ring to the classification, its relationships and also all the other 

 members of the group can be located. 



Instead of footnotes, cross references are made in the text. 

 This arrangement appears to be less distracting to the reader 

 and will also, it is hoped, bring the chapters into closer unity. 



Malcolm E. Little. 

 New York University, 

 :\Iay, 1932. 



