Introductory 



As one important object of this catalogue is to show the history 

 of each name, all references have been arranged strictly in chrono- 

 logical order and, in the case of species, the genus in which it was 

 placed b}^ each author is given if it differs from the one here adopted. 

 In the case of names higher than genera, the original form used has 

 been appended to each reference if it differs from that here employed, 

 and the category is also given where different. 



Preoccupied names are marked by a ||. 



Names cited in error by a f. 



Emendations by a t. 



Clerical errors hy s, §. 



Nomina nuda by a ^. 



The following names are proposed for the first time in this cata- 

 logue : 



Fitchiella for Xaso Fitch. 



Empoa querci var. gillettei for \'ar. bifasciata (G. & B.) 



Since the publication of the Check List in June, 1916, 263 species 

 have been added to our North American list, of which sixteen, mostly 

 Chermidae, are forms overlooked in the preparation of that list, and 

 of the remaining 247 a few are exotic forms recently recognized from 

 our territory, the balance being apparently valid new species. Ten 

 of the species included in the Check List have since been sunk as 

 synonymous of others, leaving a net gain of 253 species and making 

 the total number listed in this catalogue, 3198 accepted species. 



It will be noted that tlie original form of each name has been 

 used here, except where a typographical error is evident. This has 

 not been done with the idea of imposing upon our students the use 

 of improperly formed words. In each case all published emendations 

 have been given and eacli student is at liberty to use such emendations 

 as in his judgment may seem best. 



The table of additions and corrections was made up from the last 

 proof sent me from the printers and it is quite possible that a few 

 of the corrections included will be found to have been made on the 

 final sheets. 



An adequate recognition of the assistance received during the 

 preparation of this catalogue would embrace a wide circle of friends 

 and correspondents who have kindlj' sent me suggestions and cor- 

 rections. These have contributed much toward the accuracy and 

 value of the work and to them I wish to extend my sincere thanks. 

 Special acknowledgments are due to Professor C. W. Wood worth 



