1918 | Taylor: Revision of the Rodent Genus Anlodontia 481 
Specimens Examined.—A total of 36, from the following localities: 
California: Marin County—Five miles west of Inverness, 9; six miles west of 
Inverness, 7; four miles south of Olema, 3; Lagunitas, 2; Point Reyes, 15 (1, skull 
only; 3, jaws only, labeled under one number). 
Geographic Range—FKavorable situations in Marin County, Cali- 
fornia, where it is found within an area of approximately 110 square 
miles. 
Cranial Characters.—Skull small (see measurements below) ; nasals 
not extreme, nearly straight sided, narrow across posterior ends, not 
extremely wide at anterior ends; zygomatic arch light, not conspicu- 
ously squarish anteriorly ; temporal lines or ridges not unduly accent- 
uated, wide apart; audital tube comparatively large calibered ; fossae 
anterior of lambdoidal crests shallow ; notch dorsally on external audi- 
tory meatus shallow; incisive foramina short; interpterygoid fossa 
narrow. 
External Characters Above, 1 summer skins, pinkish cinnamon 
to cinnamon-buff, in winter approximating cinnamon or even tending 
toward sayal brown, sometimes grayish; all upperparts uniformly 
grizzled with black-tipped hairs, which are somewhat more numerous 
on the back than on the sides. Underparts French gray to plumbeous, 
with a sparse insprinkling of black hairs; the whole ventral surface 
washed with light ochraceous-buff to pinkish buff. Two specimens 
(nos. 192629, 192631, U. S. Nat. Mus., Merriam Coll.) have small white 
spots on the throat. One example (no. 192635, U. 8. Nat. Mus., Mer- 
riam Coll.) is melanistic, being light seal brown in color above and 
below. 
Age Variation.—Ilustrative of the decrease in width of the inter- 
orbital constriction with age are the measurements obtained from ten 
specimens of this species, in which the ratio of the width of inter- 
orbital constriction to basilar length varies from 26.2 per cent in a 
very young example to only 17.1 per cent in an adult. 
In several of the youngest specimens there are two small bones 
marked off by sutures in the interparietal region. They soon dis- 
appear through ankylosis. 
In ventral view it may be noted that with age the part of the palate 
between the third premolar and the incisive foramina becomes nar- 
rower. One striking feature noticed here is that while the basilar 
length varies with age in certain specimens examined from 42.9 mm. 
to 55.5 mm., the width of the palate between right and left premolar 
four remains constant at about 5 millimeters. 
