LETTER OF TRANSMITTAL. 



Office of U. S. Geological 

 and Geographical Survey of the Territories, 



Washington, D. C, December 1, 1876. 

 Sir : I have the honor to transmit herewith, for publication as one of the 

 series of Monographs of North American Rodentia, a memoir upon the fam- 

 ily Saccomyidce. 



This article is based upon the material contained in the National Museum, 

 Smithsonian Institution, including all the specimens collected by yourself, or 

 by the naturalists of the Survey under your direction. It is reproduced, with 

 additions and other modifications, from my paper entitled "A Critical Review 

 of the North American Saccomyidse", published in the Proceedings of the 

 Philadelphia Academy of Natural Sciences for 1875, pp. 272-327. 



I am, Sir, &c, 



ELLIOTT COUES, 



Assistant Surgeon U. S. A., Secretary of the Survey. 



Prof. F. V. Hayden, 



U. S. Geologist-in-charge, Sfc, Sfc. 



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