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|         | Measurements (in millimetres).
| Weight  |-------------------------------
| (in     | Total   | Tail       | Hind
| grams). | length. | vertebrae. | foot.
---------|---------|---------|------------|--------
No. 1    | 13.3    |   90    |     38     |  24
No. 2    | 12.6    |   93    |     38     |  24
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At this stage the young were partially clothed with a coat of fine velvety fur, more especially on the bodies, the tails being still nearly naked.  The body color was dark plumbeous, just the color of the dark underfur of the adult, or a shade darker, while the characteristic white markings of the adult stood out sharply as pinkish-white areas against the dark background (see Pl.  IX, Fig. 2, at p. 32).  The proportions were much as in the adult, except that the tails were relatively much shorter and the feet relatively longer.

Only one other record of young is at hand, that by Bailey, who secured the young after capture of a suckling female at Santa Rosa, N. Mex.  In this case the litter contained only one.  This was squeaking when found, but was not large enough to crawl away.  Its eyes and ears were closed, and its soft, naked skin was distinctly marked with the pattern of the adult, the colors being as given for the other two.  This juvenile lived only a week.  Young less than half grown were not trapped or noted in our poisoning operations outside the dens.

Kangaroo rats, if spectabilis be representative, reproduce at a slow rate as compared with many other small rodents.  We have records of 67 females with embryos or scars showing the number produced, and of the two litters of young described above.  Of the 69 females thus recorded, 15, or 21.7 per cent, had but one offspring each; 52, or 75.3 per cent, but two each; while only 2 individuals, or 2.9 per cent, had three.  Three young is the maximum litter recorded.  This, taken in connection with the protracted breeding season and lack of sure evidence of the production of two broods a year, gives a surprisingly low rate of reproduction, indicating relative freedom from inimical factors.

Our breeding records for merriami are fewer than for spectabilis, but are very similar in every way so far as they go, both as to the time of year and number of young.

FOOD AND STORAGE.

Dipodomys s. spectabilis does not hibernate, so must prepare for unfavorable seasons by extensive storage of food materials.  There are two seasons of the year, in southeastern Arizona at least, when storage of food takes place, namely, in spring, during April or May, and in fall, from September to November, the latter being the more important.  For the periods between, the animal must rely largely on stored materials.  Not infrequently a season of severe drought precludes the possibility of any storage.