II. The ICHNOLITES, or foot-prints, constitute a marked feature of the formation. These geological phenomena were first introduced to the notice of the public, about twenty years ago, by the late Dr. Duncan of Ruthwell, when his announcement of the tracks and foot-marks of animals along the ancient shores of Dumfries-shire created a sensation among all classes hitherto unprecedented in the history of the fossil department of the science. Robinson Crusoe was not more moved at the discovery of a human foot-print on the sands of his lonely island in the distant main, than were men of science, that traces of organic life should thus be stereotyped in a deposit believed to be utterly destitute of fossil relics. The creatures which had traced them, so like to existing walking things, greatly increased the interest and the wonder excited by the picture—the tread in all the freshness of yesterday of the inhabitants of the antediluvian world! The phenomenon, however, is now one of very general and common occurrence, several quarries in the same locality—various places in England—in Saxony—in the states of Connecticut, Massachusetts, and Virginia—having since been found to yield the impressions in the greatest abundance, and of numerous types and forms. And so well delineated and perfect are the impressions, that, in the absence of any other reminiscence of the animal, these characters have supplied the same aid to the skillful palæontologist that the fragment of a bone, a fin, or a scale, did to Cuvier and Agassiz, in the reconstruction of their organic models, and determination of extinct genera and species. Birds and reptilian quadrupeds have all contributed their share in the production of these curious lithographs. Small toe-looking scratches, deep-palmy impressions, cloven hoof-like indentations, and large gigantic hollows, have all been pictured in clear distinct outline, covered up, and now again laid patent before you as by the removal of the coverlit of your album. The Boston “Journal of Natural History” communicates the following interesting account of the researches of Dr. Deane:—“I have in my possession,” he says, “consecutive impressions of tridactyle feet, which measure eighteen inches in length, by fourteen in breadth, between the extremities of the lateral toes. Each footstep will hold half a gallon of water, and the stride is four feet. The original bird must have been four or five times larger than the African ostrich, and therefore could not have weighed less than 600 pounds. Every step the creature took sank deep, and the substrata bent beneath the enormous load. If an ox walk over stiffened clay, he would not sink so deeply as did this tremendous bird.” Sir C. Lyell has examined most of the foot-print districts in America, and found the markings so numerous in some places as to resemble the puddled stand of a sheep-fold or market-place; the very spots, doubtless, whither the