pupæ, either in the earth, in the trunks of trees, or other localities where neither beauty can betray them nor its lack screen them from the pursuit of any enemy.

As the first among the causes of colouration he places the need of protection. He points out that browns and other tertiary colours, being most readily produced by "an irregular mixture of many kinds of solar rays, are most likely to occur when the need of protection is slight, or even when it does not exist at all, always supposing that bright colours are not in any way useful to the species." Hence browns, olives, and other dirty colours may naturally be expected to predominate.

Brilliant colours, again, often serve as a sign that their wearer possesses some unpleasant or dangerous property, and hence warn possible enemies to pass on and seek some less nauseous prey. The number of apparently feeble and defenceless species which are clad in the most conspicuous colours, and which are avoided and refused by birds, monkeys, spiders, &c., is astonishing. The present writer, in a paper read before the Entomological Society (Trans. Ent. Soc., 1877, Part III., p. 205) has shown that, in a great number of cases at least, the most showy and conspicuous caterpillars feed upon plants either absolutely poisonous or possessing offensive flavours and odours, whence the rejection of such larvæ by insectivorous animals. Their brilliant colouration is therefore simply a dangersignal.

The theory of "Sexual Selection," upon which Mr. Darwin lays great weight, Mr. Wallace finds himself unable to accept as in any way an explanation of the distribution of colour in animals. He remarks that "whilst male butterflies rival, or even excel, the most gorgeous male birds in bright colours and elegant patterns, there is literally not one particle of evidence that the female is influenced by colour, or even that she has any power of choice, whilst there is much direct evidence to the contrary." In the case of the silk-moth Mr. Darwin admits that "the females appear not to evince the least choice in regard to their partners." On the principle of natural selection among a number of rival male butterflies, "the most vigorous and energetic" will probably be successful, and, as these properties are very generally correlated with intensity of colour, natural selection "becomes a preserver and intensifier of colour." Very similar is the case among birds. We know that in many species the male displays his colours and ornaments, but, as Mr. Wallace contends, there is a tota

absence of any evidence that the females admire, or even notice, this display. "The hen, the turkey, and the pea-fowl go on feeding while the male is displaying his finery) and there is reason to believe that it is his persistency and energy, rather than his beauty, which wins the day." Here, again, vigour and intense vitality seem to be the chief recommendations of the male in the eyes of the female, and these as is very strikingly manifest in the game cockappear correlated with intense colouration. Mr. Wallace resumes:- "Evidence collected by Mr. Darwin himself proves that each bird finds a mate under any circumstances. He gives a number of cases of one of a pair of birds being shot, and of the survivor being always found paired again almost immediately. This is sufficiently explained on the assumption that the destruction of birds by various causes is continually leaving widows and widowers in nearly equal proportions, and thus each one finds a fresh mate; and it leads to the conclusion that permanently unpaired birds are very scarce, so that, speaking broadly, every bird finds a mate and breeds. But this would almost or quite neutralise any effect of sexual selection, of colour, or ornament, since the less highly-coloured birds would be at no disadvantage as regards leaving healthy offspring." Whilst accepting this conclusion, we may ask whether the same argument is not capable of further application? It is generally stated that the "fittest " male-i.e., the one most in harmony with the circumstances in which he is placed-will have the best chance of securing a mate and of leaving offspring, whilst the feebler, the slower, the less energetic, and those least in harmony with the situation, will be left in a state of single blessedness, and will not transmit their attributes to posterity. But on the principles laid down in the passage we have just quoted the effects of natural selection will be greatly neutralised. It must, however, be remembered that the destruction of birds, especially in a state of Nature, will not fall exclusively or mainly upon those which have secured mates, but will likewise extend to the unwedded.

Whilst combatting Mr. Darwin's view, that the brilliant colours of butterflies have been acquired for the sake of protection, Mr. Wallace remarks :-"It is in fact somewhat remarkable how very generally the black spots, ocelli, or bright patches of colour are on the tips, margins, or disks of the wings; and as the insects are necessarily visible while flying, and this is the time when they are most subject to attacks of insectivorous birds, the position of the more conspicuous parts at some distance from the body may be a

real protection to them." This rule, however, is by no means universal. The fire-wasp (Chryseis) and not a few other Hymenoptera have brilliantly-coloured bodies, but colourless and transparent wings, which when expanded and in action are scarcely visible. In numbers of Lepidoptera the more intense colours, especially reds, are found entirely or mainly on the posterior wings, which extend to a less distance from the body than do the anterior pair. In many cases again Lepidoptera, Coleoptera, and Hymenoptera display conspicuous colours at the extremity of the abdomen, where a blow from the beak of a bird would doubtless permanently disable.

A question may here arise concerning the use of the colouration of the posterior or true wings in certain beetles, a circumstance not sufficiently examined. Whilst these wings in the vast majority of Coleopterous species are colourless, or at most of a very faint yellowish hue, in the Colorado beetle they are pink, and purple in several Chrysochroas, Pachnodas, and Lomapteras. Why should these species thus differ from other closely-allied forms, with whom they appear to agree most closely in their habits?

We have no doubt that Mr. Wallace's formal declaration against the doctrine of Sexual Selection will attract the attention of disbelievers in Evolution, and we venture to hope that all the comments which will be elicited may not be beside the question.

IV. ON THE DISCOVERY OF

STONE IMPLEMENTS IN GLACIAL DRIFT IN NORTH AMERICA.

By THOMAS BELT, F.G.S.

HE discovery of great numbers of stone implements in New Jersey, by Dr. C. C. Abbott, in deposits which are probably of Glacial age, is of such great importance that a detailed account of the beds in which they have been found and a discussion of their antiquity will be interesting to many. I had, during the past autumn, an opportunity of studying these beds under the kind guidance of the discoverer of the implements; and I am also indebted to Prof. Cook and Prof. Smock, of the Geological Survey of New Jersey, for much information respecting the glaciation of the State. I shall, in the first place, give a brief statement of what was before known of the earliest traces of man in North America.

Before these discoveries there had been many intimations of the great antiquity of man in the western hemisphere. Probably one of the earliest of these was the discovery of the fragment of a human bone which was said to have been found at the base of 60 feet of loess, near Natchez, on the Mississippi, along with the remains of the megalonyx and other extinct quadrupeds. A full description of the deposits in which these remains were discovered has been given by Sir Charles Lyell, in his "Second Visit to the States." We learn there that Dr. Dickeson, of Natchez, felt persuaded that the fragment of human bone had been taken out of the clay underlying the loam; but Sir Charles Lyell could not ascertain that it had been actually dug out in the presence of a geologist, or any practised observer, and he speculated on the possibility of it having fallen from above, into the bed of the ravine, from some old Indian grave. This was in 1846: long afterwards, when the discoveries in Europe had established the contemporaneity of man and the great extinct pachyderms, he recalled the fact

* Op. cit., vol. ii., p. 196.

that the human bone was in the same state of preservation and of the same black colour as the bones of the mastodon and megalonyx, said to have been found with it; and he was disposed to think that he had discussed its probable age with a stronger bias, as to the antecedent improbability of the contemporaneous entombment of man and the mastodon, than any geologist would now be justified in entertaining. *

The fragment of a human skull from Calaveras, in California, which was said to have been found in gravel beneath five successive overflows of lava, would, if authenticated, be probably the oldest record of man in North America. The same doubts, however, have been expressed about it as about the Natchez remains, no geologist being present when it was exhumed. In the newer gold-drifts of California, along with the remains of the mastodon, elephant, tapir, bison, and horse, the implements of man have been frequently found.t

In the auriferous gravels of Kansas and Georgia stone and flint implements have also been discovered.‡

Dr. Samuel Aughey, in his account of the superficial deposits of Nebraska, states that the remains of elephants and mastodons are often found in the loess that overspreads nearly the whole of the State. In this deposit, in a railwaycutting near Omaha, 20 feet from the surface, he dug out himself a large coarse arrow- or spear-head which lay 13 inches below the lumbar vertebra of Elephas ameri

canus.

Near Alton, in Illinois, stone axes and flint spear-heads along with the bones of the mastodon are reported from drift below loess.

All the above discoveries are in regions that drain either into the Pacific or the Gulf of Mexico.

Mr. Chas. M. Wallace has described the discovery by him of flint implements in stratified drift near Richmond, Virginia. These deposits seem to be similar to those in which Dr. Abbott has made his discoveries in New Jersey. The valley of the James River is mantled by thick deposits of coarse gravel covered with brick-clays. The implements have been found occasionally in the clay, and more frequently

Antiquity of Man, first edition, p. 200.

† J. D. WHITNEY, Geol. Surv. California, vol. i., p. 252.

560.

Dr. D. WILSON, Canadian Journal of Science, October, 1877, pp. 559,

Geol. Surv. of the Territories, 1876, p. 254.

Geol. Surv. Illinois, 1866, vol. i., p. 38.

Amer. Journ. Science, March, 1876, vol. xi., p. 195.