456 
THE CAVE MUDWALLEK. 
side, and leacliing rather more than half-way up. The inner chamber 
is reserved for the female, who there lays and hatches her eggs ; in the 
outer the male bii'd sits on guard. Such a structure is not completed 
without an extraordinary expenditure of time and labour on the part 
of both male and female. They begin, says Burmeister, by laying down 
a first course of clay which has been moistened by the rains. This is 
composed of little pellets, which the birds transport to the branch 
selected for their building operations, and spread out and flatten by 
using their feet and beak. As we have said, this mud is generally 
mixed up with vegetable matter, on the principle recognized in days of 
old that bricks cannot be made without straw. When this layer is 
eight or ten inches long, the birds surround it with a border, slightly 
bent outwards, and reaching to a height of two and a half inches, but 
raised at each end, and shaped so as to describe a concave line. Upon 
this rim or border, as soon as it is dry, is set a second and similar ledge, 
inclining slightly inwards ; then a third, and a fourth, and so on, until 
the dome-like roof is completed. As a whole, the nest may be likened 
to a small kiln or furnace nearly eight inches high, nine to ten inches 
broad, and four to six inches deep. Its weight exceeds nine pounds. 
THE CAVE MUDWALLER. 
The cave mudwaller {Acesitta cunicularia) is also a native of 
South America, inhabiting the dry plains of Chili, and the open llanos 
of the Argentine Republic, and ranging over the lofty table-lands of the 
Bolivian Cordilleras to a height of 3500 and 5000 feet above the sea. 
In his habits and characteristics the cave mudwaller seems akin to 
the lark. His plumage is of a reddish-gray, which harmonizes per- 
fectly with the tint of the soil. He appears never to perch upon bush 
or tree, and in walking he jerks his tail almost incessantly, but never 
at any time expands and folds it. In the reddish hue of his attire he 
resembles the oven-bird, and other points of likeness are his piercing 
cry and the curious staccato way in which he runs. 
The Spaniards name him casarita, or " the little mason," though 
his nest differs considerably from that of the oven-bird. He builds it, 
in fact, at the bottom of a narrow tunnel, which penetrates the ground 
