THE GROUND SQUIRRELS OP CALIFORNIA. 



707 



barriers be hewn to, such as those of climate, seacoasts, rivers, brush 

 lands and deserts. The forest ranger in anticipating the sweep of a 

 potential fire, or in combating any actual fire, outlines his campaign 

 irrespective of any but those lines which will naturally aid most in 

 stopping the spread of the conflagration. 



15. If " drive weeks" be advocated, as a popular measure to secure 

 control locally, the time of the year selected should be fixed in accord- 

 ance with the optimum chances for success, on the grounds of avidity 

 of the squirrels for kinds of bait available, minimum natural population 

 (previously to the time of appearance of the young), and probable 

 weather conditions. 



16. The above general remarks must not be construed as in any degree 

 intended to discourage the continued energetic application of the best 

 methods of ground squirrel control now in use. But it is hoped the 

 facts and inferences set forth will convince the reader that the problem 

 is not a simple one, and cannot be solved by casual, half-hearted meas- 

 ures. It is believed that great improvement can be secured both in 

 devising of method and in mode of application. 



LITERATURE CITED. 



Baird, S. F. 



1857. Mammals of North America ; the Descriptions of Species Based Chiefly on 

 the Collections in the Museum of the Smithsonian Institution. U. S. Pac. 

 R. R. Expl. and Surv., vol. 8, Part I, pp. xxxiv + 764, 60 pis. 



Gary, M. 



1911. A Biological Survey of Colorado. U. S. Dept. Agric, Bur. Biol. Surv., 

 N. Amer. Fauna no. 33, 256 pp., 12 pis., 39 figs, in text. 



Dixon, J. 



1917. Control of the California Ground Squirrel. Univ. Calif. Agric. Exper. 



Sta., circ. no. 181, 14 pp.. 3 figs, in text. 

 Elliot, D. G. 



1903. Descriptions of Twenty-seven Apparently New Species and Subspecies of 



Mammals. Field Columb. Mus., Zool. Ser., vol. 3, pp. 239-261, 2 figs, 

 in text. 



1904. Descriptions of Apparently New Species and Subspecies of Mammals and 



a New Generic Name Proposed. Field Columb. Mus., Zool. Ser., vol. 3, 

 pp. 263-270. 



1904. Catalogue of Mammals Collected by E. Heller in Southern California. 

 Field Columb. Mus., Zool. Ser., vol. 3, pp. 271-321, pis. 38-49, 1 map. 

 Finley, W. L. 



1906. The Golden Eagle. Condor, vol. 8, pp. 4-11, 6 figs, in text. 

 Grinnell, J. 



1908. The Biota of the San Bernardino Mountains. Univ. Calif. Publ. Zool., 

 vol. 5, pp. 1-170, pis. 1-24. 



1913. A Distributional List of the Mammals of California. Proc. Calif. Acad. 



Sci., 4th ser., vol. 3, pp. 265-390, pis. 15, 16. 



1914. An Account of the Mammals and Birds of the Lower Colorado Valley with 



Especial Reference to the Distributional Problems Presented. Univ. 

 Calif. Publ. Zool., vol. 12, pp. 51-294, pis. 3-13, 9 figs, in text. 



1918. Six new Mammals from the Mohave Desert and Inyo Regions of California. 



Univ. Calif. Publ. Zool. vol. 17, pp. 423-430. 

 Grinnell, J., and Grinnell, H. W. 



1907. Reptiles of Los Angeles County, California. Throop Inst. Bull., no. 35, 64 



pp., 23 figs, in text. 



115 



