20 



NOBTH AMEKICAK FAUNA. 



[No. 38. 



COLORS. 



The names of colors used tlirougliout the text are those of Ridg- 

 way.^ On account of iridescence and reflection of light from the fur 

 the color of any single animal may appear to vary considerably when 

 viewed from different angles. For this reason the following method 

 of making comparisons and observations of colors was used consist- 

 ently: Diffused daylight from a window was allowed to strike the 

 animal at an angle of 30° to 45° posterior to a plane perpendicular to 

 the median longitudinal line of the animal. The mole was then 

 viewed from its anterior end at an angle of about 60° from the light 

 rays and in the same plane with them. In spite of this care colors 

 have sometimes been exceedingly difficult to determine and describe. 



MATERIAL AND ACKNOWLEDGMENTS. 



The present revision recognizes 28 forms of 10 species of Amer- 

 ican moles and is based upon a study of 2100 specimens, mostly skins 

 accompanied by skulls. Of this number, Scalopus comprised 945, 

 Scapanus 604, Parascalops 129, CoTidylura 218, and Neilrotrichus 204. 

 While type specimens or essential topotypes of all described forms 

 have been examined, the material has been inadequate for an 

 entirely satisfactory understanding of the group, and this is partic- 

 ularly true of the genus Scapanus, and of Scalopus from some of the 

 southern and western parts of its range. Unreliable determinations 

 of sex also have been a serious handicap. 



Although the study has been based primarily upon specimens in 

 the Biological Survey and other collections in the United States 

 National Museum, including the Merriam collection, it became evi- 

 dent early in the investigation that this material would be insufficient 

 for a proper elucidation of the group. Accorduigly specimens were 

 borrowed from various museums and private collections until nearly 

 all that were available in the United States and Canada were exam- 

 ined. For the loan of specimens and for various other courtesies I 

 wish to express my appreciation to the following: Dr. J. A. Allen, of 

 the American Museum of Natural History; Mr. Samuel Henshaw 

 and !Nir. Outram Bangs, of the Museum of Comparative Zoology, 

 Harvard College; Dr. Joseph Gritmell, of the Museum of Vertebrate 

 Zoology of the University of California; Mr. Charles B. Cory and 

 Mr. W. H. Osgood, of the Field Museum of Natural History; Dr. Wit- 

 mer Stone, of the Academy of Natural Sciences of Philadelphia; 

 Dr. W. J. Holland and Mr. W. E. Clyde Todd, of the Carnegie 

 Museum; Mr. H. L. Ward, of the Public Museum of the City of Mil- 

 waukee; Dr. A. G. Euthven, of the University of Michigan Museum 



1 Ridgway, R., Color Standard, . J d Color Nomenclature, 1912. 



