the snowy owl assists it in getting its prey, or that its color hampers the raven. The northern weasels and northern hares of America both turn white in winter. Thru most of their range the various species of these weasels and hares exist side by side with the close kinsmen of the weasel, the mink and the sable, and at the southern boundary of their range side by side with the small gray rabbits; none of which change their color any more than the lynx and fox do, and yet in the struggle for life seem to be put to no disadvantage thereby. The Arctic hare changes color as does the ptarmigan. The ordinary snow-shoe rabbits and jack-rabbits of the woods and plains south of the Arctic hare region also change their color; but the grouse which inhabit the same woods or open plains, such as the ruffed, the sharp-tailed and the spruce, unlike their northern kinsman, the ptarmigan, undergo no seasonal change. Around my ranch on the Little Missouri, the jack-rabbits all turned white in winter; the little cotton-tail rabbits did not; yet as far as I could see both species were equally at home and fared equally well.

When a boy, shooting on the edges of the desert in Egypt, I was imprest with the fact that the sand grouse, rosy bullfinches, sand larks and sand chats all in the coloration of their upper parts harmonized strikingly with the surroundings, while the bold black and white chats were peculiarly noticeable, and yet as far as I could see held their own as well in the struggle for existence. But as regards the first-named birds it seemed to me at the time that their coloration was probably protective, for in the breeding season the males of some of them showed striking colors, but always underneath, where they would not attract the attention of foes.

Mr. Selous also shows that the "signal" or "mutual recognition" theory of coloration has been at the least carried to an extreme by closet naturalists. The prongbuck of North America has the power of erecting the glistening white hairs on its rump until it looks like a chrysanthemum; but there seems scarcely any need of this as a signal; for prongbucks live out on the bare plains, never seek to avoid observation, are very conspicuous beasts, and have eyes like telescopes, so that one of them can easily see another a mile or two off. According to my experience—but of course the experience of any one man is of limited value, and affords little ground for generalization—the "chrysanthemum" is shown when the beast is much aroused by curiosity or excitement.

Mr. Selous' chapters on the lion possess a peculiar interest, for they represent without any exception the best study we have of the great, tawny, maned cat. No one observer can possibly cover the entire ground in a case such as this, for individual animals differ markedly from one another in many essential traits, and all the animals of one species in one locality sometimes differ markedly from all the animals of the same species in another locality (as I have myself found, in some extraordinary particulars, in the case of the grizzly bear). Therefore, especially with a beast like the lion, one of the most interesting of all beasts, it is necessary for the naturalist to have at hand the observations of many different men; but no other single observer has left a record of the lion of such value to the naturalist as Mr. Selous.

One of the most interesting of Mr. Selous' chapters is that containing his notes on wild dogs, on hunting hounds, and on cheetahs. Especially noteworthy are his experiences in actually running down and overtaking by sheer speed of horse and hound both the wild dog and the cheetah. These experiences are literally inexplicable with our present knowledge; and therefore it is all the more valuable to have them recorded, Mr. Selous' own account of the speed of wild dogs and the statements of many competent observers about cheetahs—as for instance, of that mighty hunter, Sir Samuel Baker—make it clear that under ordinary circumstances both wild dogs and cheetahs, when running after their game, go at a speed far surpassing that of a horse. Yet in these instances given by Mr. Selous, he and his companions with their camp dogs once fairly ran down a pack of wild dogs; and twice he fairly ran down full-grown cheetahs. In the last case it is possible that the hunted cheetah, not at first realizing his danger, did not put forth his full speed at the beginning, and, not being a long-winded animal, was exhausted and unable to spurt when he really discovered his peril. But with the hunting dogs it is hard to imagine any explanation unless they were gorged with food. In coursing wolves with greyhounds, I have noticed that the dogs will speedily run into even an old dog wolf, if he is found lying by a carcase on which he has feasted, under conditions which would almost certainly have insured his escape if he had been in good running trim. I once saw a cougar, an old male, jump from a ledge of rock surrounded by hounds and come down hill for several hundred yards thru the snow. The hounds started almost on even terms with him, but he drew away from them at once, and when he reached the bottom of the hill, was a good distance ahead; but by this time he had shot his bolt, and after going up hill for a very few yards he climbed into a low evergreen tree, which I reached almost as soon as the hounds. His lungs were then working like bellows, and it was obvious he could have gone no distance further.

The book of nature has many difficult passages, and some of them seem mutually contradictory. It is a good thing to have capable observers who can record faithfully what they find therein, and who are not in the least afraid of putting down two observations which are in seeming conflict. Allied species often differ so radically in their habits that, with our present knowledge, not even a guess can be made as to the reason for the difference; this makes it all the more necessary that there should be a multitude of trustworthy observations. Mr. Selous points out, for instance, the extraordinary difference in pugnacity between the fighting roan and sable antelopes, on the one hand, and on the other, the koodoo and the mild eland. There is quite as great difference between far more closely allied species, or even between individuals of one species in one place and those of the same species in another place. Sometimes the reasons for the difference are apparent; all carnivores in India, with its dense, feeble population, would at times naturally take to man-killing. In other cases, at least a guess may be hazarded. The wolf of America has never been dangerous to man, as his no larger or more formidable brother of Asia and Europe has been from time immemorial; yet the difference may be accounted for by the difference of environment. But it is hard to say why the cougar, which is just about the size of the great spotted cats, and which preys on practically the same animals, should not be dangerous to man, while they are singularly formidable fighters when at bay. The largest cougar I ever killed was eight feet long and weighed over two hundred pounds. Very few African leopards or Indian panthers would surpass these measurements, and this particular animal had been preying not only on deer, but on horses and cattle; yet I killed him with no danger to myself, under circumstances which would probably have insured a charge from one of the big spotted cats of Africa or Asia, or, for the matter of that, from a South American jaguar. And by the way, in reading of the ravages committed by leopards among the hounds of the sport-loving planters of Ceylon, it has always seemed to me strange that these planters did not turn the tables on the aggressors by training packs especially to hunt them. Such a pack as that with which I have hunted the cougar and the black