ON THE “GILA MONSTER.” 3 
a dog. Fora while the sand was dug out directly, until 
it began to pour back; then a position was taken up on 
the top of the heap that had been made, and it was thrown 
still farther back ; gradually working forward, conditions 
were soon made favorable for continuance of excavation 
at the bottom of the burrow. At the depth of about a 
foot the body was hidden and only the tail exposed. This 
depth appeared to be satisfactory for a time, and the dwell- 
ing was occupied as if complete. 
The tail is club-shaped, near six inches in length by one 
and a half in diameter, and retains its thickness back tow- 
ard the end where it rather abruptly tapers to become more 
slender and pointed. When the tail was sticking out of the 
excavation, as in digging, the slender extremity moved 
from side to side, back and forth and around, with more 
flexibility than was to be expected from its size, as if con- 
stantly on the alert for unseen danger. The organ is very 
sensitive. While asleep the tail was stowed as if to in- 
sure its safety; it was either extended directly back into 
the burrow, half of the body remaining outside, or, when 
the animal was wholly under cover, it was bent forward 
along the side. In sleep, the body lies flat on the sand 
and the arms were usually stretched back, palms upward. 
After a few weeks, less care was taken in regard to enter- 
ing the burrow during the day, and the naps were taken 
anywhere in the box. 
The box was not well placed for the sunshine; it was 
covered with a strong netting. Some attempts to get 
through the net one morning caused the occupant to be 
taken by the shoulders and lifted over into another cage 
where he might get the full benefit of the sun. This was 
quietly enjoyed until the sun had_ passed, then there 
was another attempt on the cover, followed by return to 
the first box and retreat into the hole. This came to be the 
