We saw on the banks screamers—­big, crested waders of archaic type, with spurred wings, rather short bills, and no especial affinities with other modern birds.  In one meadow by a pond we saw three marsh-deer, a buck and two does.  They stared at us, with their thickly haired tails raised on end.  These tails are black underneath, instead of white as in our whitetail deer.  One of the vagaries of the ultraconcealing-colorationists has been to uphold the (incidentally quite preposterous) theory that the tail of our deer is colored white beneath so as to harmonize with the sky and thereby mislead the cougar or wolf at the critical moment when it makes its spring; but this marsh-deer shows a black instead of a white flag, and yet has just as much need of protection from its enemies, the jaguar and the cougar.  In South America concealing coloration plays no more part in the lives of the adult deer, the tamandua, the tapir, the peccary, the jaguar, and the puma than it plays in Africa in the lives of such animals as the zebra, the sable antelope, the wildebeeste, the lion, and the hunting hyena.

Next day we spent ascending the Sao Lourenco.  It was narrower than the Paraguay, naturally, and the swirling brown current was, if anything, more rapid.  The strange tropical trees, standing densely on the banks, were matted together by long bush ropes—­lianas, or vines, some very slender and very long.  Sometimes we saw brilliant red or blue flowers, or masses of scarlet berries on a queer palm-like tree, or an array of great white blossoms on a much larger tree.  In a lagoon bordered by the taquara bamboo a school of big otters were playing; when they came to the surface, they opened their mouths like seals, and made a loud hissing noise.  The crested screamers, dark gray and as large as turkeys, perched on the very topmost branches of the tallest trees.  Hyacinth macaws screamed harshly as they flew across the river.  Among the trees was the guan, another peculiar bird as big as a big grouse, and with certain habits of the wood-grouse, but not akin to any northern game-bird.  The windpipe of the male is very long, extending down to the end of the breast-bone, and the bird utters queer guttural screams.  A dead cayman floated down-stream, with a black vulture devouring it.  Capybaras stood or squatted on the banks; sometimes they stared stupidly at us; sometimes they plunged into the river at our approach.  At long intervals we passed little clearings.  In each stood a house of palm-logs, with a steeply pitched roof of palm thatch; and near by were patches of corn and mandioc.  The dusky owner, and perhaps his family, came out on the bank to watch us as we passed.  It was a hot day—­the thermometer on the deck in the shade stood at nearly 100 degrees Fahrenheit.  Biting flies came aboard even when we were in midstream.