30 



ISrOETH AMERICAN FATJN^A. 



[no. 39. 



great diversity of climatic and physical features and partly from the 

 fact that it has been the most thoroughly studied of the Western 

 States. The magnificent series of specimens in the Museum of 

 Vertebrate Zoology of the University of California has not only 

 added to the number of species known in the State, but has greatly 

 helped in defining the ranges of local species and correlating them 

 with the distribution areas. 



MATERIAL EXAMINED. 



In the present study of the genus Thomomys over 7,300 specimens 

 have been examined. Of these, 4,166 are in the Biological Survey 

 collection and 475 in the other collections of the National Museum. 

 Of the remaining specimens examined, 1,755 are in the Museum of 

 Vertebrate Zoology, 276 in the American Museum of Natural His- 

 tory, 234 in the Field Museum of Natural History, 177 in the Museum 

 of Comparative Zoology, 131 in the Stanford University collection, 

 90 in the Academy of Natural Sciences of Philadelphia collection, and 

 smaller numbers from the Victoria Memorial Museum, the Pro- 

 vincial Museum of British Columbia, the Kansas University collection, 

 the Oregon Fish and Game Commission collection at Reed CoUege, 

 the California Academy of Sciences collection, the North Dakota 

 Agricultural CoUege Museum collection, and private collections of 

 Mr. E. R. Warren, Mr. Stanley G. Jewett, Mr. W. D. Hollister, Dr. 

 William Bebb, and Mr. Ernest Thompson Seton. 



For the use of this material, which has in every case been most 

 cordially loaned, my appreciation is elsewhere expressed. 



All of the types now in America (83 in number) have been ex- 

 amined, and through the courtesy of Mr. Oldfield Thomas a good 

 photograph of the skall of the type of T. umbrinus has been pro- 

 vided and also notes on the old types in the British Museum. Of 

 the eight types not examined, five (T. talpoides, T. umhrinus, T. 

 atrovarius, T. alticola, and T. anitse) are in the collection of the 

 British Museum. Good series of topo types of all of these have been 

 available for study, and also topotypes of T. hulhivorus and T. douglasi, 

 the types of which appear to be no longer in existence. Unfortu- 

 nately the type of T. talpoides is imperfect, lacking most of the sknQ, 

 but a good series of virtual topotypes have been available for study. 



The type of T. hottse in the Museum d'Histoire Naturelle, at Paris, 

 has not been seen, but large series of specimens from the type region 

 have been examined. 



The study of this material shows many localities where a few speci- 

 mens would throw much light on the zonal distribution and relation- 

 ships of species, and brings up many problems that can be settled 

 only by careful field study and the collection of specimens at many 



