Next I must, if possible, obtain conclusive evidence as to the use to which the ants put the seeds thus collected; whether they eat them or turn them to some other account. Again I must observe whether the seed-collecting ants also search for aphides, and what other kinds of food they obtain. Then another very interesting question remained--namely, whether all southern ants uniformly collect seed, and to the same extent, or whether the habit is peculiar to certain species. These, and many other subjects of inquiry connected with them, readily suggested themselves to my mind, and it will now be my endeavour to show how far I have been able to throw light upon them. The habits recorded in the following pages refer exclusively, unless special notice is given to the contrary, to _Atta barbara_, the black ant represented on Plate I. We have, as far as I am aware, only four _bonâ fide_ harvesting ants on the Riviera--namely, _Atta barbara_ under two forms, the one wholly black the other red-headed; _Atta structor_, a creature very similar to _barbara_, but of a claret-brown colour; and a minute yellow ant, the large workers of which have gigantic heads, named _Pheidole_ (or _Atta_) _megacephala_. My renewed observations at Mentone were carried on from October, 1871, to May, 1872, and I was able during that interval to become a frequent visitor to a warm and sheltered valley, which lay but a few minutes' walk from the house in which I lived, and in which thirty nests of the most active of the seed-storing ants were to be found. Full therefore of my intention to resolve this difficulty if possible, I set out on October 29, 1871, immediately after my return to Mentone, to revisit this valley, where, in the previous May, I had seen the ants busily engaged in cutting, carrying, and sorting their harvest. The spot in question was a rough slope of soft sandstone rock, with accumulations of sandy soil in the hollows, covered with a sparse and scrubby vegetation, composed of _Cistus_ (_C. salvifolius_), pot-herb thyme, black lavender (_Lavandula stæchas_), spiny broom (_Calycotome spinosa_), overshadowed here and there by a few scattered stone and maritime pines, and intermixed with coarse grasses and some smaller plants. Cultivated lemon terraces lay on the edge of the wild ground lower down in the valley, and at this season, as also in the late spring, these terraces were overgrown with a rank crop of weeds, most of which were in seed. I had scarcely set foot on the _garrigue_, as this kind of wild ground is called, to distinguish it from meadows or terraced land, before I was met by a long train of ants, forming two continuous lines, hurrying in opposite directions, the one with their mouths full, the others with their mouths empty.