1887] Description of a New Species of Dipodomys. 43 
The proportions of the two species are much the same. There 
are other points of difference in the skull, but this is sufficient to 
show their specific distinctness. 
D. phillipsi ordi, being a slightly larger, rufous-tinged variety of 
D. phillipsi, may be considered as being classed with the latter 
in the above comparison. 
The type specimen may be below the average size. I havea 
male that measured (fresh) 5.8 inches head and body, 8.2 inches 
tail vertebræ. Total number of specimens examined is nine. 
The photographs of skulls are natural size; of the animal, three- 
fourths natural size. 
The last three days of June, 1886, I camped near the Mojave 
River on my way home from a collecting trip along the desert 
side of the San Bernardino Mountains. The first morning there 
(June 29) I found two peculiar Dipodomys in traps I had set the 
previous evening. They seemed to be a pale variety of D. 
phillipsi, such as I knew to be liable to occur there, it being the 
rule that most birds and mammals inhabiting the Mojave and 
Colorado Deserts are paler in color than others of the same 
species found in the moister coast region. In another trap was 
an ungrown D, philips: of nearly normal color, but I laid its 
darker color to its evident immature condition. At sunset I 
again put out my traps, and, as there were more inhabited 
burrows than I had traps for, I put out poisoned wheat also, 
which proved a most unwise act. This poisoned wheat is widely 
used in California to destroy ground-squirrels, pocket-rats, and 
similar pests. When it is used, some of the poisoned animals 
come to the surface to die, and I expected to obtain some ad- 
ditional specimens by its use. The next morning I had one 
D. phillipsi and two of the pale variety in my traps, and I found 
one of each phase of coloration poisoned, and, later in the day, 
when the hot sun had spoiled it, I found another pale one. 
Nearly all the poisoned wheat had been taken. These additional 
specimens convinced me that the pale animals were a good species. 
I had intended driving on in the afternoon, but I concluded to 
stop another night to try for more. The poisoned wheat had 
done its work only too well, for my traps contained no pocket- 
rats the next morning, and but few burrows showed signs of 
occupancy. I was unable to revisit the region until the next 
November, when I followed the Mojave River for twenty-five 
