Doubtless the earth and the vegetable matter had merely been taken incidentally, adhering to the viscid tongue when it was thrust into the ant masses.  Out in the open marsh the tamandua could neither avoid observation, nor fight effectively, nor make good its escape by flight.  It was curious to see one lumbering off at a rocking canter, the big bushy tail held aloft.  One, while fighting the dogs, suddenly threw itself on its back, evidently hoping to grasp a dog with its paws; and it now and then reared, in order to strike at its assailants.  In one patch of thick jungle we saw a black howler monkey sitting motionless in a tree top.  We also saw the swamp-deer, about the size of our blacktail.  It is a real swamp animal, for we found it often in the papyrus-swamps, and out in the open marsh, knee-deep in the water, among the aquatic plants.

The tough little horses bore us well through the marsh.  Often in crossing bayous and ponds the water rose almost to their backs; but they splashed and waded and if necessary swam through.  The dogs were a wild-looking set.  Some were of distinctly wolfish appearance.  These, we were assured, were descended in part from the big red wolf of the neighborhood, a tall, lank animal, with much smaller teeth than a big northern wolf.  The domestic dog is undoubtedly descended from at least a dozen different species of wild dogs, wolves, and jackals, some of them probably belonging to what we style different genera.  The degree of fecundity or lack of fecundity between different species varies in extraordinary and inexplicable fashion in different families of mammals.  In the horse family, for instance, the species are not fertile inter se; whereas among the oxen, species seemingly at least as widely separated as the horse, ass, and zebra species such as the domestic ox, bison, yak, and gaur breed freely together and their offspring are fertile; the lion and tiger also breed together, and produce offspring which will breed with either parent stock; and tame dogs in different quarters of the world, although all of them fertile inter se, are in many cases obviously blood kin to the neighboring wild, wolf-like or jackal-like creatures which are specifically, and possibly even generically, distinct from one another.  The big red wolf of the South American plains is not closely related to the northern wolves; and it was to me unexpected to find it interbreeding with ordinary domestic dogs.

In the evenings after dinner we sat in the bare ranch dining-room, or out under the trees in the hot darkness, and talked of many things:  natural history with the naturalists, and all kinds of other subjects both with them and with our Brazilian friends.  Colonel Rondon is not simply “an officer and a gentleman” in the sense that is honorably true of the best army officers in every good military service.  He is also a peculiarly hardy and competent explorer, a good field naturalist and scientific man, a student and