IV PEEFATOEY NOTE. 



Should no unforeseen circumstance prevent, the Bulletins will continue 

 to be issued at convenient irregular intervals, as material may come to 

 hand; the strictly serial character of the publication being maintained. 

 The actual date of issue is given on the temporary cover of each, as it 

 is important to fix with precision the appearance of the successive num- 

 bers of a periodical in which so many new genera and species are de- 

 scribed. 



This publication, answering so fully the special purpose for which it 

 was established, is regarded as one of the most important means to the 

 main ends which the Survey has in view. It has already acquired a 

 character and standing which render it favorably comparable to the 

 regular "Proceedings" or other similar publications of any of the learned 

 b >dies of this country or Europe. Its scope includes the whole range 

 of the subjects for the investigation of which the Survey is conducted, 

 and the appearance of which in this connection does not in any way 

 restrict the plan of the formal Eeports of the Survey. The volumes 

 already issued contain articles upon Archaeology, Ethnography, Lin- 

 guistics, Geology, Topography, Geography, Palaeontology, and Natural 

 History in general, suitably illustrated with plates, cuts, and maps; and 

 no effort'will be spared in the future to maintain the high standard 

 which the present volume so conspicuously illustrates. 



The thanks of the Survey are due to Dr. Elliott Coues, U. S. A., for 

 his careful and able conduct of the ptriodical. 



F. V. HAYDEN, 

 United States Geologist. 



