PREFACE TO FIRST EDITION. 
ha we may accept the hypothesis, generally acknowledged, 
that efficiency of the few is attained only under the 
stimulas of the inefficient many, no apology is needed for 
another addition to the already numerous text-books in 
existence. It is questionable whether it is possible to 
provide the student with a book which can entirely take 
the place of oral instruction, but it is intended in the 
present work to provide the necessary accompaniment to 
a well-ordered course of lectures and practical work. 
Although there are still science “Schools” in existence in 
which practical instruction is entirely neglected or relegated 
to unqualified teachers, the importance of this branch of 
education is being generally recognised: hence I have 
written the discriptions of the types in this book, and in 
the majority of cases have drawn the figures, with the 
animals (or the parts of them) before me, in order that 
the work may be found an aid to dissection as well as a 
preparation for written examinations. 
So far as is possible the scope of the work has been 
largely modelled on the subject “Natural History,” as 
interpreted in our Scottish Universities, and the method 
of instruction by types has been adhered to as conducing 
to the best results. 
Ina volume of this kind which must necessarily hold in 
view the necessities of examinations, there is a very definite 
limit to the introduction of new features of classification 
or even of new types, and a continual check has to be 
applied to the inclination to add this or that new result, 
