Plate III., p. 23.--The floors of three granaries of _Atta barbara_, surrounded by the much coarser gravelly earth, of the natural size. Plate IV., p. 31.--A mass of earth pierced by roots, in which the ants (_Atta barbara_) have made their granaries and galleries. The galleries were full of seeds when first laid open. Of the natural size. Plate V., p. 33, fig. A.--Galleries and terminal cells of a nest of _Atta barbara_, excavated in the living sandstone rock, drawn _in situ_, of the natural size; B, part of a cylindrical gallery from another rock-nest, and B 1, the same gallery seen in front, of the natural size. Plate VI., p. 35, fig. A.--A sprouting hemp-seed, part of the radicle of which has been gnawed by the ants, of the natural size; A 1, the same, magnified, _rad._ radicle; A 2, an entire sprouting seed of the same, magnified; B, a sprouting pea, part of the radicle of which has been gnawed off; B 1, the same, magnified; B 2, the same stripped of its coat, and showing the two seed leaves; C, a sprouting "canary-seed" (the grain of _Phalaris canariensis_), part of the fibril of which has been gnawed off; C 1, the same, magnified, _rad._ the radicle which remains undeveloped, and _fib._ the fibril or first rootlet; C 2, an unmutilated sprouting "canary seed;" D, a mass of earth taken out of the heart of a nest of _Atta barbara_, in which a spherical cell, made of hardened earth, was buried. It contained grass seeds, among which I found ants at work, and seeds of the same grass still in their husks lay in the gallery leading up to the entrance of this cell; D 1, the same, further freed from the earth, and having part of one side removed, so as to show the interior and the small lower opening leading out from the bottom of the cell. PART II.--TRAP-DOOR SPIDERS.