s at a time
in some years, and the consequent failure of green succulents show that
without doubt _spectabilis_ possesses remarkable power, as to its water
requirements, of existing largely if not wholly upon the water derived
from air-dry starchy foods, i.e., metabolic water serves it in lieu of
drink (Nelson, 1918, 400), this being formed in considerable quantities
by oxidation of carbohydrates and fats (Babcock, 1912, 159, 170). During
the long dry periods characteristic of southern Arizona, no evidence
that the animal seeks a supply of succulent food, as cactus, is found;
and if it may go for two, three, or six months without water or
succulent food, it is reasonable to suppose that it may do so
indefinitely. In the laboratory _spectabilis_ ordinarily does not drink,
but rather shows a dislike for getting its nose wet. During the periods
of drought the attacks upon the cactuses by other rodents of the same
region, as _Lepus_, _Sylvilagus_, _Neotoma_, and _Ammospermophilus_,
become increasingly evident. The list of plant species thus far found
represented in the storage materials of _spectabilis_ on the Range
Reserve is shown in Table 3.

TABLE 3.--_List of all plant species found in 22 dens of _Dipodomys
spectabilis_ on the United States Range Reserve, near the Santa Rita
Mountains, Ariz., with approximate total weights._

GRASSES.
Grams.
Aristida bromoides (six-weeks needlegrass) 536
Aristida divaricata (Humboldt needlegrass) 9,412
Aristida scabra (rough needlegrass) 344
Bouteloua aristidoides (six-weeks grama) 3,093
Bouteloua radicosa (grama) 1,269
Bouteloua eriopoda (black grama) Tr.
Bouteloua rothrockii (seeds, 8,495; crowns, 3,517 grams)
(crowfoot grama) 12,012
Festuca octoflora (fescue grass) 70
Panicum arizonicum (Arizona panic-grass) 11
Panicum hallii (Hall panic-grass) Tr.
Pappaphorum wrightii Tr.
Tridens pulchella Tr.
Valota saccharata Tr.