ILLUSTRATIONS, 



PLATES. 



(Following page 36.] 



Plate I. Skulls (dorsal views) of Cynomys ludovicianus ludovicianus, C. I. arizonensis, 

 and C. mexicanus, and (posterior views) of C. I. ludovicianus and C. I. 

 arizonensis. 



II. Skulls (ventral views) of Cynomys ludovicianus ludovicianus, C. I. ari- 

 zonensis, and C. mexicanus, and mandibles of C. I. ludovicianus and C. 

 mexicanus. 



III. Skulls (dorsal views) of Cynomys leucurus, C. parvidens, C. gunnisoni 



gunnisoni, and C. g. zuniensis. 



IV. Skulls (ventral views) of Cynomys leucurus, C. parvidens, C. gunnisoni 



gunnisoni, and C. g. zuniensis. 

 V. Skulls (lateral views) of Cynomys ludovicianus ludovicianus, C. I. arizo- 

 nensis, C. mexicanus, C. parvidens, C. gunnisoni gunnisoni, and C. g. 

 zuniensis. 



YI. Skulls (dorsal and ventral views) of two individuals of Cynomys ludo- 

 vicianus ludovicianus from the same locality. 

 VII. Skulls (various views) of Cynomys ludovicianus ludovicianus, C. mexicanus, 

 C. gunnisoni gunnisoni, C. parvidens, and C. leucurus. 



TEXT FIGURES. 



Pago. 



Fig. 1. Distribution of subgenus Cynomys (Cynomys ludovicianus ludovicianus, 



C. I. arizonensis, and C. mexicanus) 13 



2. Distribution of subgenus Leucocrossuromys (Cynomys leucurus, C. par- 

 videns, C. gunnisoni gunnisoni, and C. g. zuniensis) 24 



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I 



