to the present accomplisliment. A total of 1263 study skins of ground squirrels taken within this state have been examined in the course of our work.
In the spring and summer of 1911, two field assistants from the United States Public Health and Marine-Hospital Service were assigned by Dr. Rupert Blue, then Surgeon in Command, San Francisco, to accompany the Museum party working in south-central California, for the purpose of increasing the common knowledge of the distribution and manner of occurrence of the rodents of the region. Acknowledgment is here made for the use of certain facts from the manuscript report of that year's work made to Dr. Blue by the Director of the Museum.
During the past year, Dr. W. C. Billings, Surgeon, in temporary charge, United States Public Health Service, San Francisco, has very greatly aided us in having his field men send us specimens of ground squirrels, both alive and dead, for experimentation and study.
To Professor Harvey M. Hall, of the University of California, we are indebted for identifying numerous seeds obtained from the cheek-pouches of ground squirrels.
Through special provision of the State Commissioner of Horticulture we have been fortunate in being able to have the accompanying five colored plates of ground squirrels drawn by the eminent animal artist, Mr. Louis Agassiz Fuertes. We thank Mr. Fuertes for the special pains he has taken in executing these drawings.
Color terms used in our descriptions are taken from Ridgway's Color Standards and Color Nomenclature (1912).
Information used by us from published sources is credited through the system of author, year and page references to the list of "Literature Cited" which appears at the end of this paper. The authority for important information obtained from field notebooks or from letters is given in parenthesis together with the abbreviation for the word manuscript—"MS."
Joseph Grinnell.
Joseph Dixon.
September 13, 1918.
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