GEOMYS. 



CRATOGEOMYS. 



311 



FIG. 56. GEOMYS ARENARIUS. 

 No. 36114 U. S. Nat. Mus. Coll. Nat. size. 



UPPER TOOTH ROW. LOWER TOOTH ROW. 



Enlarged 7 times. Enlarged 7 times. 



Color. Above drab brown, lined with black; under parts and 

 feet white. 



Measurements. Total length, 258; tail vertebrae, 88; hind foot, 

 33. Skull: basal length, 37.5-40.5; Hensel, 34-37; zygomatic width, 

 24-28; interorbital breadth, 6-7; length of upper molar series, 7.5-8; 

 length of single half of mandible, 27-28.5. 



<>tt. Cratogeomys. Powerful Pocket Gophers. 



Cratogeomys Merr., Mon. Geom., N. Am. Faun., No. 8, 1895, p. 



150, pis. and figs. Type Geomys merriami Thomas. 

 Upper incisor with a single groove, usually open; upper premolar 

 with three enamel plates, posterior absent; shaft convex forward; 

 upper and lower premolars subequal in length. First and second 

 upper molar with one enamel plate each, posterior absent. Last 

 upper molar with a deep sulcus on outer side, none on inner. Skull: 

 a depression extends obliquely across squamosals from root of zygoma 



