834 The American Naturalist. [September, 
torridus and of the same proportions, but with a relatively longer man- 
dible and higher coronoid process 
Measurements.—Total length, 147; tail, 48; hind foot,18; ear, 
from crown, 12. 
I have examined the type of torridus, with which ramona shows 
closer affinities than with any other member of the genus. Making 
allowance for the facts the type was “ skinned out of alcohol,” and the 
skull is missing, it is easy to see that torridusis externally a very differ- 
ent looking mouse from ramona, being lighter and more unicolor above 
and lacking the bright vinaceous wash on the sides. 
Adopting the cranial and superficial characters given for torridus by 
Dr. Merriam in North American Fauna, No. 2, the two are best dis- 
tinguished as follows: 
Onychomys torridus. Onychomys ramona. 
1. Above, uniform dull, tawny 1. Above, grayish vinaceous buff. 
cinnamon. 
2. No darker dorsal stripe. 2. Darker grayish dorsally. 
3. No black ring around eye. 3. Narrow, black ring round eye. 
4. Tail with dark dorsal stripe 4. Tail with dark dorsal stripe, 
reaching three-fourths its seven-eighths to nine-tenths its 
length. length. 
5. Average measurements :— 5. Average measurements (five 
length, 135; tail, 45; hind- adults) :— length, 139; tail, 
foot, 20 ; ear, from crown, 10. 48; hind-foot, 19; ear, from 
crown, 13. 
CRANIAL MEASUREMENTS. 
torridus | ramona 
Basilar length (of Hensel) 18.5 19. 
= zygomatic breadth 12.5 12.6 
arietal 11.4 11.5 
eal constriction 4.2 5. 
Length of nasals 9.6 10. 
Foramen-magnum to incisive NANI, -anara 125 19.4 
Alveolar length of upper molar series 3.5 3.8 
Length of mandible. 13.2 15. 
Height of coronoid process from angle 5.8 6.8 
