94 
JOUENAL OF MAMMALOGY 
and Vancouver ensis, and in the picatus series there is individual varia- 
tion tending to bridge the gap in either direction. The indentation in 
the orbital arch, given by Osgood as a feature distinguishing petulans 
from Vancouver ensis, is not a character to be absolutely relied upon. 
This httle notch is sharply indicated in the petulans series, as I beheve 
it is in the red squirrels of the interior of the northwest generally. In 
the Vancouver Island skulls at hand there are none in which it is at all 
deeply cut. In some it is entirely absent, but usually there is a sug- 
gestion of a notch at that point. The southern Alaskan series contains 
none in which the notch is as nearly eliminated as in most of the Van- 
couver Island skulls, and as a rule it is as apparent as in the petulans 
series. It is not a character the presence or absence of which can 
be indicated in each of the skulls; it appears in all degrees from one 
extreme to the other. 
Berkeley, California. 
REVISED LIST OF THE SPECIES IN THE GENUS DIPODOMYS^ 
By Joseph Grinnell 
A bare hst of names is a pretty poor offering, not ordinarily worth 
printing. But in the present revised hst enumerating sixty species and 
subspecies of kangaroo rats a good deal of new information is set forth in 
a concentrated form. The main basis of this contribution is a relatively 
extensive systematic and distributional study of the genus as occurring 
within the hmits of Cahfornia. The more comprehensive report upon 
this study is hkely to be long delayed in the press, if, indeed, it ever 
sees the light of pubhcation. 
The 33 forms now known to occur in this state (Cahfornia) have 
been determined upon after examination of a large amount of material, 
over 2800 skins with skulls. Confidence as to their status is much 
greater than with most of the remaining forms, of which material has 
been accessible in only scant amount. Still, first impressions, as gained 
of the latter, may be worthy of consideration, when gathered upon the 
basis of the rather intensive study of the other forms. 
The ‘‘ordii group” is accepted practically as revised by Goldman 
(Proc. Biol. Soc. Washington, vol. 30, 1917, p. 113). 
1 Contribution from the Museum of Vertebrate Zoology of the University of 
California. 
