Birds were not abundant, the fall migrations having left the forest almost deserted. The few species which remained, however, such as wood-hewers, thrushes, tanagers, and jays, were plentiful, and several kinds of humming-birds added life and color to the sombre green of the vegetation. After many days we succeeded in tracing the mysterious chirp to its source, and found, not the bird we were seeking, but a dainty little wood-wren of the shyest possible nature. The minute, secretive creature seemed to spend its entire time among the buttresses, roots, and moss-draped undergrowth, where no ray of sunlight ever penetrated to dispel the chill and semidarkness, or give a touch of warmth to the soggy mould. Its glimpses of daylight must be brief indeed, and at infrequent intervals. We had come to the mountains in a state of enthusiasm and expectancy, for here it seemed we should succeed in ending our long quest for the tapacola. As the days passed, thrilling excitement gave way to exasperation, and finally disappointment alone remained to fill the void created by the flight of the other emotions. We returned to Tucuman for a brief time, and then struck for the forest farther south. This time we left the railroad at a station called Acherál two and one-half hours from Tucuman, and camped in the forest at the foot of the ridge. Again we were doomed to disappointment. Birds were more abundant than at Villa Nougués, but the tapacola was not forthcoming. There were, however, numerous other interesting species. Pigmy woodpeckers (_Picumnus_) selected the patches of high brush and second-growth woods just without the edge of the forest proper. They are little larger than a good-sized humming-bird, dark or black above, white underneath, and have a red cap. Their industrious hammering always advertised the presence of a pair as they hopped quickly along the trunks and branches, tapping for worms or excavating a nesting-site. The woods were undermined with tunnels made by the queer _tuco-tuco_, or _oculto_ (_Ctenomys_), a species of which we had come in contact with in Brazil. We set a steel trap in one of the subterranean runways, carefully covering with a log the opening we had made; soon a series of low grunts emanated from the spot, and we found a fine, large specimen of the strange rodent safely held by the steel jaws. Bottle flies were so numerous as to prove a most disagreeable pest. Blankets, clothing, food, and specimens alike were covered with “blow” if left exposed for but a few minutes. We were lucky in possessing enough netting with which to rig up covers for everything, but even then numbers gained entrance, and we had to clean the infested articles frequently by passing them over a fire or by scraping and brushing.