126 Proceedings of the Biological Society of Washington. 



Subspecific characters. — Similar in color and cranial characters to R. 

 mexicanus ludfrons (described above), but decidedly smaller; upper parts 

 slightly paler, except on the head, which is similar to the back. 



Description of type. — Head and upper parts sayal brown, varied with 

 fuscous; sides pale sayal brown; ears fuscous; eye-ring black; feet dull 

 white, with a median stripe of hair-brown; tail fuscous, unicolor; underparts 

 white, faintly washed with pale pinkish cinnamon. 



Measurements. — Type: Head and body, 69 mm.; tail vertebrae, 102; 

 hind foot (dry), 18.5; earfrom notch (dry), 11. Skull: Greatest length, 21.4; 

 breadth of brainoase, 11.1; length of nasals, 7.5; width of outer wall of 

 antorbital foramen, 1.5. 



Remarks. — The single specimen of this form at hand is clearly referable 

 to the mexicanus group, and doubtless wiU prove to be a subspecies, nearest 

 related to ludfrons. Although resembling the latter closely in color, its 

 distinctly smaller size indicates that it represents a separate race. 



