2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 94 



INTRODUCTION 



One of the chief justifications for the study of the morphology 

 of any group of organisms is the importance of this branch of the 

 science in the classification of those organisms. Morphology is one of 

 the important foundations of classification because it supplies the 

 easiest and most usable key to the relationships between individuals. 

 The discovery and evaluation of these relationships is an important 

 part of our attempts at classification. 



The purpose of such a morphological study as this may be stated 

 as follows : In the first place, it is an attempt to increase the knowl- 

 edge of the external morphology of the Staphylinidae as a basis for 

 a better understanding of their classification. It is furthermore an 

 attempt to add something to the knowledge of the morphology of 

 beetles in general. This very large and important field has been so 

 poorly explored up to the present time that any attempts to make ad- 

 ditions are not only justified but very much to be desired. 



In any very large group of animals the number of species whose 

 morphology can be investigated in detail is necessarily limited by con- 

 siderations of time and expense of publication. Any conclusions drawn 

 from the comparatively few representatives examined must neces- 

 sarily be only tentative and suggestive, and they must await the less 

 detailed examination of the numerous other species for confirmation. 



The large order Coleoptera is one of the best known of all the groups 

 of insects. One of the largest included families is the Staphylinidae. 

 containing approximately one-tenth of all the known species of beetles. 

 The study of this family, however, has been relatively neglected 

 and the list of known species probably does not include one-fifth of 

 those actually in existence, and even from North America it is doubt- 

 ful if over one-half the sj^ecies have been recorded. This condition 

 is due to the difficulties which attend the study of this family when 

 it is carried on by the methods formerly employed by many ento- 

 mologists — methods which fail to provide an adequate knowledge of 

 the comparative morphology of the group. These difficulties vanish 

 in large part when the study is approached in the right manner. 



To a student of the Coleoptera desiring to undertake a comparative 

 morphological study of some group as a basis for its classification, 

 the family Staphylinidae has much to commend it. It is sufficiently 

 large to show a wide range of structure ; the total number of species 

 is large enough to provide ample material for the full development 

 of one's ideas of the principles of classification ; a great number of 

 its members are common enough to be very easily obtained ; the ma- 



