viii PREFACE. 



not only be made familiar with the essentials of -vertebrate 

 organisation, but should be so drilled in details as to be 

 capable of working out, with some degree of thoroughness, 

 any ordinary vertebrate animal which may be set before 

 him. 



The advantage of the study of Comparative over that of 

 Human Anatomy lies in the fact that in the former the dry 

 facts are, to borrow an expression of Dr. Michael Foster's, 

 "salted with the salt of morphological ideas." But if the 

 same thoroughness in practical work is not demanded of 

 the student of Animal Morphology as of the medical student, 

 if he is allowed to shirk the discipline of laborious dissection, 

 and to be content with a " general notion " of the structure 

 of the types he examines, he runs a very serious risk of 

 getting uncommonly little meat to his salt, and of losing 

 in depth what he gains in breadth. 



It was therefore necessary to decide how much might be 

 left out without leading the student into a superficial way 

 of working ; and in striving to " keep the mean between the 

 two extremes of too much stiffness in refusing and of too 

 much easiness in allowing" any omissions, I am only too 

 well aware how largely the personal equation enters into 

 questions of this sort, and how unsatisfactory the 

 compromise I have decided upon may seem to other 

 teachers. 



The subjects described are mostly such as can be readily 

 obtained at any time of the year. The Skate is chosen in 

 preference to the more typical Dogfish, partly because it is 



