32 BULLETIN 18 2, UNITED STATES NATIONAL MUSEUM 



in the descriptions, it seems worth while in enabling one to have 

 a complete picture of the genus without having to consider a series 

 of "species inquirendae." If these keys be found to be faulty, it 

 will seldom affect the species I had before me but only the doubtful 

 ones. Before each specific name in the key is a number indicating 

 the position of that species in the sequence of the text. 



Very careful attention has been given to the specific synonymies. 

 Although the Junk catalog has again been used as a starting point, 

 a large amount of synonymy has been found that is not recorded 

 in that already voluminous work. In addition, each species is re- 

 corded under each generic name with which it has ever been coupled. 

 In general, I have tried to cite all references to each species, but 

 in the case of cosmopolitan species this is obviously impracticable. 

 In such cases, only the original reference is given. The date and 

 page refer to the detailed citations in the bibliography. 



Throughout the work the descriptions have been arranged on a 

 uniform pattern. The color and markings are given first; then the 

 details of the head, pronotum, elytra, and abdomen, with their ap- 

 pendages, in that order; the special characters of the male and the 

 female; the special characters of the legs; and finally the length. 

 Throughout each genus I have tried to mention the same characters 

 in the same order and manner to facilitate comparisons. Certain 

 terms and usages are explained in a later paragraph. 



There is a strong and highly commendable tendency among mod- 

 ern entomologists to give exact dimensions in the descriptions of 

 insects. Doubtless these are of great value in many groups. How- 

 ever, in the Staphylinidae there is almost always a considerable 

 range of size due to at least two factors: (1) The actual difference in 

 size of individuals; and (2) the apparent difference caused by 

 greater or less retraction of the flexible abdomen. A very exact 

 measurement of total length is of little use if the specific range is 

 great. Since in the present work direct measurements have not been 

 found to be of great value, the length is given in millimeters and 

 major fractions thereof, and all minor measurements are given as 

 proportions of one part to another. These are expressed as frac- 

 tions rather than as ratios because they have thus been found to be 

 more readily understandable and comparable. 



Several factors have prevented the use of primary genitalic charac- 

 ters in the descriptions. The first of these was the lack of time to 

 develop techniques and make the numerous dissections and prepara- 

 tions. Another was the fact recently demonstrated in other studies 

 that some genera do not present usable specific characters on the 



