LETTER TO THE GEOLOGIST IN CHARGE. 



Washington, D. C, January 1, 1873. 



Dear Sir : During my connection, for the past four years, with the Geo- 

 logical Survey of the Territories conducted under your charge, I have been 

 enabled to collect a large number of specimens of Orthoptera, especially of 

 Acrididge ; and having made the study of this family a specialty for several 

 years past, I conceived the idea of preparing a monograph or synopsis of the 

 species thereof found in the United States. Having mentioned this idea to 

 you, I am happy to say that you heartily approved of it, and gave me all the 

 encouragement and aid therein consistent with the other and more practical 

 duties of the Survey. By this encouragement and aid, and the use of the 

 name of the Survey, I have succeeded in collecting together a large number 

 of specimens, representing not only almost all the previously-described spe- 

 cies, but also a jiumber of new ones, most of which have been described and 

 reported, from time to time, for publication in your annual reports; a few are 

 herein noticed for the first time. I herewith present the result of my labors 

 in this direction, trusting that it may prove acceptable, and that it may con- 

 tribute something, be it ever so small, to the advancement of scientific knowl- 

 edge. It is possible that a delay of another year would have enabled me to 

 render it more complete and satisfactory ; but I have conclude<l it is best to 

 bring it before the public as soon as possible, as it will be one aid to ento- 

 mologists in determining new species, and thus enable them the sooner to 

 complete the Hst of the species of this important family which belong to the 

 North American fauna. I have entitled it a "Synopsis," instead of "Mono- 

 graph," because I have not had an opportunity of inspecting all the described 

 species, nor of examining many of the original types of other authors. 



In order to render it as complete and as useful as possible, I have added 

 descriptions of the species found in other parts of North America, but 

 whicli do not belong to the United States fauna. These descriptions arc 

 chiefly from the authors by whom they were originally described, as I have 

 had an opportunity of inspecting but few of the species, and very few of 

 them have been figured. 



