134 Proceedings of the Biological Society of Washington . 



General characters. — Resembling S. obscums but considerably larger 

 and with slightly darker coloration. 



Color. — Upperparts dull sepia brown with less reddish than in obscurus ; 

 lower parts with brownish suffusion quite strongly contrasted with the 

 gray belly of obscurus. 



Skull. — Conspicuously larger and heavier than in obscurus with rela- 

 tively smaller third premolar. 



Measurements. — Type: total length, 118; tail vertebrae, 45; hind loot, 

 15. Adult 9 topotype: 106; 42; 14; another 9 : 115; 45; 14. Skull of 

 type: greatest length, 18.4; basal length, 16.5; greatest width of brain- 

 case, 8.8; length of tooth row, 8; greatest width across molars, 5. Same 

 measurements of an adult 9 : 18.5; 1(1.4; 8.5; 7.8; 5. 



