The types of all the new species which I have described have been placed 

 in the Agricultural Department, where they will be preserved, thus aflTording 

 a ready means of reference in future investigations. Quite a number of these 

 have been figured by Professor Townend Glover, and will be found in his 

 " Illustrations of North American Entomology — Orthoptera," published in 

 quarto during the past season. 



An examination of this synopsis will show that about one hundred and 

 twenty species of this family, exclusive of the Tettiginas, are described as 

 belonging to the United States, and as representing twenty-five genera. 

 The total number of Aci'ididas, exclusive of Tettiginas, described in Fischer's 

 Orthoptera Europea, is but seventy-seven, representing twenty genera. I 

 have described as new forty species and four genera, and have also inti'o- 

 duced six other genera not hitherto known to be represented in the United 

 States. In two instances I have adopted generic names (equivalents) differ- 

 ent from those used by Mr. Scudder : this has been done in order to conform 

 to the present usage of European orthopterologists. I have modified and 

 somewhat changed the arrangement of the entire order, Fieber's system, con- 

 sidered as descending, being used as a basis ; but I find since the publication 

 of your last report (1871), in which I sketched this arrangement, that I 

 have been in part anticipated by Brunner de Wattenwyl, of whose plan I 

 have seen but an outline. I have adopted an arrangement of the various 

 divisions of the family, which I may claim, in great part at least, as my own ; 

 whether valuable or not must be determined by future investigations and use. 



I take pleasure in'acknowledging the favors received from the Smithso- 

 nian Institution in the preparation of this work ; and also desire to express 

 my thanks to the Agricultural Department for the use of the specimens of 

 Orthoptera deposited there, and for the assistance rendered in procuring 

 specimens from various parts of the United States. 

 Very respectfully, your obedient servant, 



CYRUS THOMAS. 



Professor F. V. Hayden, 



United States Geologist. 



