8 THE CONDOR VoL XV birds. The latter gave attention indeed, but would not heed the repeated warn- ings. My advances had the effect of bringing all the flock together, whereas otherwise they would have scattered over the entire ledge of, say, a hundred feet length. Now and again the flock shifted, but always they came back, alighting at the extreme tip of the reef where the waves frequently bandied them. For the most part they fed silently, but as often as I made some unusual demonstration or as often as the wave swept about them, a murmur of complaint arose. The flock came to attention, or a few shifted position, if the water was actually too deep. But the moment danger was over, work was resumed upon the barnacles. My last exposure. the last of twenty-one plates, was made at a distance of eighteen feet, and at that range only half of the flock would go on the plate. The exposure (f. I6, I-I4O ? was perfectly timed, and it marked, I am proud to con- fess, the most thrilling moment of a ten-year experience in bird photography. Fig. 6. SURF-BIRDS: THE PARTING SHOT From a pho[ogml0h. copyright. 1913. by W. L. Dawson CONCEALING AND REVEALING COLORATION OF ANIMALS* By JUNIUS HENDERSON ONCEALMENT is o/aly one factor of safety and not always the most im- portant factor. There are numerous others, such as the sharp hearing, keeu scent and speed of deer and antelopes, the weapons and strength of ele- phants and tigers, the protective armor of turtles and armadillos, the shells of clams and oysters, the spines of sea urchins and porcupines, the offensive or ir- ritative secretions or stench of certain invertebrates, which render concealment comparatively unimportant in many cases. Natural selection means the survival, not of those forms which have a single advantageous character, but of those whose combined characters as a whole best fit them for existence in their natural environment, surrounded by their natural enemies. Hence the very popular supposition that under the doctrine of natural selection all animals must be concealingly colored, is unwarranted in theory and unsupported by the facts. If a given species be varying in the direction of con- cealing coloration and in no other direction. naturally those forms, or routants, or whatever we wish to call them, whose colors are in closest harmony, would be
- Abstract of an address before the University of Colorado Scientific Society.
