238 NATURAL HISTORY. 



Before concluding this article, it remains to say a few words on the FOSSIL FORMS,* which 

 are very few in number. With regard to Palaeontology, the numerous papers published by Pro- 

 fessors Owen and Huxley in Great Britain, Professor Alphoiise Milne-Edwards in France, and 

 the masterly researches carried on by Professor O .0. Marsh, of Yale College in America, have thrown 

 a flood of light upon the ancient forms of the class Aves, before almost wholly unknown, and have 

 to a great extent removed those barriers which seemed before to separate birds completely as a class 

 from the rest of the Vertebrata. 



That the presumed existence of birds at the period of the Secondary rocks should have been first 

 intimated by their footprints may seem strange, but as far back as 1835, a notice appeared in " Silli- 

 man's Journal," stating that Dr. Deane had discovered impressions resembling the feet of birds upon 

 some slabs of red sandstone from Connecticut. Dr. Hitchcock was the first who submitted these 

 tracks to careful scientific investigation, and concluded that they had been produced " by the feet of 

 birds." These gigantic three-toed footprints have been found in more than twenty places, scattered 

 through a tract of country nearly eighty miles in extent, and they are repeated through strata more 

 than one thousand feet in thickness, t Upwards of two thousand of these Ornithichnites had been 

 observed and examined by Professor Hitchcock several years ago ; but notwithstanding the most 

 diligent and careful search, not a vestige of organic remains of either bird or pterodactyl has as yet 

 been discovered in these beds. Numerous coprolites occur in the Connecticut rocks, and Dr. Dana has 

 very ingeniously argued, from the analysis of their bodies, that, like guano, they are the droppings of 

 birds rather than of reptiles. 



The fossil footprints exhibit regularly, where the joints are seen, the same number as exists in the 

 feet of living three-toed birds, and in each continuous line of tracks the three-jointed and five-jointed toes 

 are placed alternately outwards, first on one side and then on the other. In some impi-essions, besides 

 the three toes in front, the rudiment of the fourth toe is seen behind. It is not often that the matrix 

 has been fine enough to retain impressions of the integument, or skin of the foot, but in one specimen 

 found by Dr. Deane at Turner's Falls, on the Connecticut River, these markings are well preserved, 

 and were recognised by Professor Owen as resembling the skin of the Ostrich and not that 

 of reptiles. 



Later researches, however, tend to prove that these footprints are not, after all, those of birds ; 

 for Professor Marsh, in his address to the American Association for the Advancement of Science, 

 in 1877, remarks : "A careful investigation of nearly all the specimens yet discovered, has con- 

 vinced me that there is not a particle of evidence that any of these fossil impressions were made by 

 birds. Most of these three-toed tracks were certainly not made by birds but by quadrupeds, 

 which usually walked upon their hind feet alone, and only occasionally put to the ground 

 their smaller anterior extremities. I have myself detected the impressions of these anterior 

 limbs in connection with the posterior footprints of nearly all of the supposed ' bird-tracks ' described, 

 and have little doubt that they will eventually be found with all. These double impressions 

 are precisely the kind which Dinosaurian reptiles would make, and as the only characteristic bones 

 yet found in the same rocks belong to animals of this group, it is but fair to attribute all these foot- 

 prints to Dinosaurs, even where impressions of fore-feet have been detected, until some evidence 

 appears that they were made by birds. I have no doubt that birds existed at this time, although at 

 present the proof is wanting." 



Of the ArchcKOpteryx from the Oolitic beds we have already spoken, and passing on from the 

 Oolitic to the Cretaceous formation, we still find remains of birds exceedingly rare. But, just as in 

 the preceding series of beds, land-surfaces and fresh-water deposits are few in number, and terrestrial 

 organic remains are consequently uncommon. In 1840, under the name of Cimoliornis diomedeus, 

 Professor Owen described a leg and a wing-bone of a longipennate natatorial bird, equalling the 

 Albatross in size ; but the subsequent discovery by Dr. Bowerbank of several additional bones and 

 a part of the head, led that careful observer to conclude that these remains belonged to a ptero- 

 dactyl, and not to a bird, as first supposed by Owen. As long ago as 1 858, true bird-remains had 

 been discovered by Mr. Lucas Barrett in the Upper Greensand, near Cambridge, a formation 



* For assistance in this portion of the article the author is indebted to his friend, Dr. Henry Woodward, F.R.S. 

 t Lyell's "Manual of Geology," 5th Edition, p. 348. 



