30 SPERMOPHILES OP THE MISSISSIPPI VALLEY. 



the only object being to keep the gas in, and to see if any of the inmates 

 dig out afterwards. * * * The dead animal is thus buried and out 

 of sight in his own burrow, creates no stench and poisons nothing; its 

 flesh would not be injurious even if dug up. No other wild or domestic 

 animal runs any risk, unless it be the gopher. The holes retain an 

 offensive odor for some time, and remain closed and untenanted. * * * 

 As for the expense of this method, I have freed the most thickly-peo- 

 pled portions of the University campus (level ground) from every ves- 

 tige of squirrels with about a pound of the liquid per acre; about half 

 an hour being spent by two men in closing the holes with shovels." * 



During the past five or six years this remedy has been recommended 



by the Division, and has been used with success by numerous corre- 



spondents. Mr. Joseph Conaster, of Sunset, Wash., who was much 



troubled by the depredations of Townsend's Spermophile, after using 



1 the poison, wrote under date of July 20, 1892 : 



" I think your bisulphide will exterminate the squirrels. Have anni- 

 hilated two towns of them that I have been shooting and poisoning for 

 three years. Did it all in two hours and am satisfied that the bisul- 

 phide will be the grand remedy of all." 



KEY TO THE SPECIES. 



The area covered by this bulletin includes the ranges of five sper- 

 mophiles. One of these, Kennicott's Spermophile, is a sub-species of 

 the peculiar Sonoran Spermophile (8. sxnlosoma). A sixth form, the 

 Wyoming Spermophile, closely related to SpennopMhis richardsoni, 

 will be mentioned and its distribution included under the latter species, 

 as data is wanting to limit the ranges of the two animals. 



These five species differ widely from one another in coloration, and 

 may be readily distinguished by the colors and markings of the back. 

 For convenience in identification they are here divided into three 

 groups as shown below. 



KEY TO THE FIVE MISSISSIPPI VALLEY SPERMOPHILES. 



1. Back striped lengthwise. 



(a) With solid stripes alternating with rows of spots, Spermophilus tridecemli- 

 neatus. 



(b) With rows of spots without any solid stripes Spermophilus mexicanus. 



2. Back irregularly and indistinctly spotted. 



Size small, tail short and slender Spermophilus spilosoma obsoletus.i 



3. Back not distinctly striped or spotted; size large. 



(a) Tail long and bushy, gray Spermophilus franhlini. 



(&) Tail short, buff below, blackish above Spermophilus richardsoni. 



* Bulletin of the University of California, No. 32, April, 1878. 



t This spermophile inhabits western Nebraska, and is gray in color, with blackish 

 edgings to the spots. It belongs to the Spermophilus spilosoma group, most of the 

 members of which are yellowish brown in color. They are not mentioned in the 

 present report because the main part of their range is to the south and west of the 

 area here treated. Representatives of the group however occur in southern and 

 western Texas and eastern Colorado. 



