BULLETIN OF THE LABORATORIES 
thus the danger of freezing solid is obviated. The earth is used in 
plastering the outside of the hut, though this is not systematically 
done. A curious habit we have occasionally observed is the thatching 
of the hut with the large water-lily leaves so overlapping and cement- 
ed with mud as to form an impervious roof. By this time the ice is 
beginning to form and the hut has settled as much as it will, being 
buoyed up by the ice. The rats now burrow into the house from near 
the bottom forming a passage in the form of a letter U inverted, the 
uppermost part being above the water level and here a small chamber 
is excavated. Run-ways are excavated beneath the ice to various 
parts of the pond. In the long excursions undertaken beneath the ice 
the rats are said to ascend to the ice and exhaust the lungs, permitting 
the expired air to absorb oxygen and then reinspire it. This we have 
never been able to observe. The roots of Nuphar are built into the 
house or are stored conveniently near for winter use. The great mass 
of vegetable matter soon begins to ‘Teat” generating warmth enough 
not only to add to the comfort of the occupants of this curious home 
but to cause new sprouts to spring from the roots. The chamber is 
enlarged during the winter and the part removed serves to supply food 
in case of outside famine. The outer layer of mud freezes solid and 
forms an adequate defense against the wolves which might otherwise 
wage a war of extermination. There seems to be a certain reciprocity 
between the occupants of adjacent lodges, although the rats are jeal- 
ous by nature and have not the communistic characters of the beaver, 
though no whit inferior to them as architects. 
As to the statement commonly believed by woodcraftsmen in the 
West that the muskrat prearranges his hut in view of the length and 
severity of the coming winter we can offer nothing definitely. There 
is, however, a wide variation in respect to the size and structure of 
the huts and a general correspondence though by no means a univer- 
sal one, between the huts built during a given season. An average 
hut is 6x10 feet in diameter at the water’s edge and the size of the 
chamber varies from i8 inches to two feet. 
The Pocket Gopher or Pouched Rat, Geomys biirsarius, al- 
though abundant west of the Mississippi, is probably unfamiliar to 
most non-professional observers. This animal is nevertheless the rep- 
resentative of one of the most interesting and distinctive of North 
American mammals. 
