(4) _Dipodomys s. spectabilis_ is nocturnal; it is gentle, and does not offer to bite when taken in the hand; is silent for the most part; active; somewhat sociable with its fellows, but fights in defense of its food stores; progresses chiefly by leaping; signals by a drumming or tapping on the ground with its hind feet. (5) The breeding season of _spectabilis_ begins in January and continues into August. Whether more than one litter is raised in a single season is unknown. The number of young in each litter varies from 1 to 3, averaging 2. (6) _Dipodomys s. spectabilis_ does not hibernate, but provides food stores, mostly seeds, for use during seasons when food would be otherwise unavailable. Storage in each den varies in quantity from 5 grams (about 1/6 ounce) to 5,750 grams (12.67 pounds). Materials stored include several important forage plants; for example, various species of _Bouteloua_ and _Aristida_, with _B. rothrockii_ (crowfoot grama) the most important. Accessibility and abundance of different plants have much to do with the kinds of storage found. (7) The dens of _spectabilis_ are the most notable of all kangaroo rat dwelling places. They range from 6 inches to 4 feet in vertical height, and from 5 to 15 feet in diameter. Here the kangaroo rat has its home, shelter, and food-storage chambers. Within the den is found a tortuous network of burrows, with many storage and some nest chambers, the whole arranged so as to be two to four stories high. (8) _Dipodomys s. spectabilis_ is not of great economic significance, except locally, in ordinary seasons. During periods of extreme drought it may be of critical importance on grazing areas from the standpoint of the carrying capacity of the range. (9) Kangaroo rats are easy to poison by following the same formula as that used by the Biological Survey for destroying prairie dogs. (10) In many places unsuited to extensive grazing or agriculture _spectabilis_ does no appreciable damage. It is one of the most interesting of all the rodents peculiar to our Southwestern deserts, and should not be molested except where it is destructive. BIBLIOGRAPHY. ALLEN, J. A. 1895. On a collection of mammals from Arizona and Mexico, made by Mr. W. W. Price, with field notes by the collector. Bull. Amer. Mus. Nat. Hist., vol. 7, art. 6, pp. 193-258. 17 figs. in text. BABCOCK, S. M. 1912. Metabolic water: Its production and role in vital phenomena. Research Bull. No. 22, Univ. Wisconsin Agr. Exp. Station, pp. 159 and 170, March. BAILEY, V. 1905. Biological survey of Texas. North Amer. Fauna No. 25, Biol. Surv., U. S. Dept. Agr., pp. 222, 16 pls., 24 figs. in text. CLEMENTS, F. E. 1905. Research methods in ecology. Lincoln, Univ. Pub. Co., pp. xvii, 334, 85 figs. in text. GRIFFITHS, D. 1910. A protected stock range in Arizona. Bull. No. 177, Bur. Plant Ind., U. S. Dept. Agr., pp. 28, 6 pls., 1 fig. in text. GRINNELL, JOSEPH.