The habits of these three species are similar, and they evidently replace each other in the natural economy of the different islands; nor can I point out any difference between their habits and those of _M. Thenca_ of Chile; I imagined, however, that the tone of their voice was slightly different. They are lively, inquisitive, active birds, and _run_ fast; (I cannot assert, positively, that _M. Thenca runs_). They are so extremely tame, a character in common with the other birds of this Archipelago, that one alighted on a cup of water which I held in my hand, and drank out of it. They sing pleasantly; their nest is said to be simple and open. They seem to prefer the dry sterile regions nearer the coast, but they are likewise found in the higher, damper and more fertile parts of the islands. To these latter situations, however, they seem chiefly attracted by the houses and cleared ground of the colonists. I repeatedly saw the _M. melanotis_ at James Island, tearing bits of meat from the flesh of the tortoise, which was cut into strips and suspended to dry, precisely in the same manner as I have so often observed the _M. Orpheus_, in La Plata, attacking the meat hung up near the Estancias. 1. FURNARIUS RUFUS. _Vieill._ Furnarius rufus, _Vieill._, Ency. Meth. 513. Merops rufus, _Gmel._ Pl. enl. 739. Opetiorhynchus rufus, _Tem._ Man. Turdus vadius, _Licht._ Cat. Figulus albogularis, _Spix_, Av. pl. lxxviii. f. 1 & 2. Fournier, _Buff._, _Azara_, No. 221. This bird is common in Banda Oriental, on the banks of the Plata; but I did not see it further southward. It is called by the Spaniards Casaro, or housebuilder, from the very singular nest which it constructs. The most exposed situation, as on the top of a post, the stem of an opuntia, or bare rock, is chosen. The nest consists of mud and bits of straw; it is very strong, and the sides are thick; in shape it resembles a depressed beehive or oven, and hence the name of the genus. Directly in front of the mouth of the nest, which is large and arched, there is a partition, which reaches nearly to the roof, thus forming a passage or ante-chamber to the true nest. At Maldonado, in the end of May, the bird was busy in building. The Furnarius is very common in Banda Oriental; it often haunts the bushes in the neighbourhood of houses; it is an active bird, and both _walks_ and _runs_ quickly, and generally by starts; it feeds chiefly on Coleoptera; it often utters a peculiar, loud, shrill, and quickly reiterated cry. 2. FURNARIUS CUNICULARIUS. _G. R. Gray_. Alauda cunicularia, _Vieill._ Alauda fissirostra, _Kittl._ Mem. l’Acad. St. Peters, ii. pl. 3. Certhilauda cunicularia, _D’Orb. & Lafr._ Mag. de Zool.