18 
BULLETIN 1091, TJ. S. DEPARTMENT OF AGRICULTURE. { 
Technical 
Bull. No. 1, 
Measurements (in millimeters). 
Weight 
(in 
grams). 
Total 
length. 
Tail 
vertebrae. 
Hind 
foot. 
No. 1. 
No. 2. 
13.3 
12.6 
90 
93 
38 
38 
24 
24 
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 character- 
istic 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 Bosa, 
X. Mex. In this case the litter contained only one. This was squeak- 
ing 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 speetdbUis be representative, reproduce at a 
slow rate as compared with many other small rodents. AVe 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 re- 
corded. This, taken in connection with the protracted breeding sea- 
son 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 spectabiJis, 
but are very similar in every way so far as they go. both as to the 
time of year and number of young. 
Dipoclomys s. spectahills 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 
FOOD AND STORAGE. 
