NO. 13 STAPH YLINIDAE BLACK WELDER 7 



and the figures showing variation have for the most part not been 

 burdened with interpretations of structure. It is beHeved that this 

 latter will be obvious upon comparison with the morphological fig- 

 ures. As far as possible, all unusual or extreme structures are described 

 in the text. 



The figures have all been drawn directly from slide mounts by 

 means of a camera lucida. No attempt has been made to indicate or 

 calculate the magnification attained, as this is believed to be purely 

 incidental and of no importance to a knowledge of the morphology. 

 Figures have been drawn to uniform sizes to show comparable details 

 in the different species regardless of the original size. 



The abbreviations used are the same on all the figures and are listed 

 and explained at the end of the paper. They are for the most part the 

 same as those adopted by Snodgrass in his recent papers. 



It should be borne in mind that each figure is more or less of a 

 composite, having been checked with as many specimens as possible 

 and frequently drawn from parts of several. 



MORPHOLOGY OF THE STAPHYLINIDAE 

 General Considerations 



Because of the fact that there does not exist any single work which 

 deals in any considerable degree of completeness with the comparative 

 morphology of the Coleoptera as a whole, it has not been possible 

 to adopt any one system of study or any single terminology. In the 

 case of those structures that have been separately studied in a compre- 

 hensive way, an attempt has been made to follow that work in general. 

 A very large part of the structure of beetles, however, has never 

 been monographed comparatively, with the result that the present 

 study has necessarily been built upon the basic works of Snodgrass 

 and others, in which the Coleoptera are treated only as a whole along 

 with the other orders of insects. 



In the case of the structure of the head capsule, the interpretation 

 adopted here is that worked out by Snodgrass and Boving. Its ap- 

 plications to the order Coleoptera have not previously been presented. 



The orientation of the legs is a matter of common inconvenience. 

 The fundamental position of the leg is assumed to be as follows: 

 The leg is extended at right angles to the body, with each part ex- 

 tended distally and the empodium of the pretarsus facing downward, 

 the coxa suspended from the body by the condyles at its proximal 

 end. Following this orientation, it is possible to see four chief asi^ects 

 of the leg, the anterior and the posterior, and the dorsal and the 



