Ord’s Kangaroo Rat 
ings through any one of which the little rat could plunge down 
to his subterranean dwelling. These openings led to a rather in- 
tricate series of passageways opening one into the other in such 
a way as to lead the intruder to another exit rather than to the 
nest. The latter he found was reached by a short branch lead- 
ing from one of the above passageways, the mouth of which was 
apparently plugged up with earth by the little animal before de- 
parting, so as to further shield the nest from any intruders. The 
nest had a thick felting of fine grass and weed silk and a soft 
lining of feathers. Two other chambers were filled with over a 
pint of sunflower seeds and evidently served as _ storehouses. 
Of the mouse itself, which Mr. Thompson kept for a time in 
captivity, he writes: ‘‘He was the embodiment of restless energy. 
Palpitating with life from the tip of his translucent nose and ears 
to the end of his vibrant tail. He could cross the box at a single 
bound, and I now saw the purpose of his huge tail. In the 
extraordinary long flying leaps that Perodipus makes the tuft 
on the end does for him what the feathers do for an arrow. 
They keep him straight in the air in his trajectory. 
He was the most indefatigable little miner that I ever saw. Those 
little pinky-white paws, not much larger than a pencil point, 
seemed never weary of digging, and would send the earth out 
between his hind legs in little jets like a steam-shovel. He 
seemed tireless at his work. He first tunnelled the whole mass 
through and through and | doubt not made and unmade several 
ideal underground residences and solved many problems of rapid 
underground transit. Then he embarked in some landscape garden- 
ing schemes and made it his nightly business to entirely change 
the geography of his whole country, laboriously making hills and 
canyons wheresoever seemed unto him good.” Mr. Thompson had 
reason to suppose that the faint bird-like twitterings sometimes 
heard at night by cowboys and others on the plains are to be 
attributed to the Percdipus, being analogous to the songs which 
are uttered by some individuals of the common house mouse and 
the white-footed mouse of our woods. 
