CONTENTS. 



Page. 



Letter of transmittal : 3 



List of illustrations 7 



Introduction 9 



Plan of the investigations 11 



Correspondence 11 



Field work 13 



Laboratory work 13 



Natural enemies of spermophiles 15 



Bounties 18 



Objections to the bounty system 22 



Methods of destroying prairie dogs and spermophiles 24 



Firearms 25 



Fumigation : 25 



Traps 1 25 



Poisoning 25 



Experiments with bisulphide of carbon 27 



Key to the species 30 



Striped Prairie Spermophile (SpermopMlus tridecemlineatus) 31 



Mexican Spermophile (SpermopMlus mexicanus) 46 



Franklin's Spermophile (SpermopMlus franhlini) 48 



Kennicott's Spermophile (SpermopMlus spilosoma obsoletus) 58 



Richardson's Spermophile ( SpermopMlus richardsoni) 59 



6 



