It was a startling announcement, and a conclusion that must have had strong evidence to support it, since one of the kinds of the tracks had been made by a pair of feet, each leaving a print 20 inches in length. Under the term Orni thichnites gigantems, however, Dr. Hitchcock did not shrink from proclaiming the fact of the existence, during the period of the deposition of the red sandstones of the valley of the Connecticut, of a bird which must have been at least four times larger than the ostrich.* The impressions succeeded each other at regular intervals ; they were of two kinds, but differing only as a right and left foot, and alternating with each other, the left foot a little to the left, and the right foot a little to the right, of the mid-line between a series of tracks. Each footprint (fig. 84, b and r) exhibits three toes, diverging as they extend forwards. The distance between the tips of the inside and outside toes of the same foot was 12 inches. Each toe was terminated by a short strong claw projecting from the mid toe a little on the inner side of its axis, from the other two toes a little on the outer side of theirs. The end of the metatarsal bone to which those toes were articulated rested on a two-lobed cushion which sloped upwards behind. The inner toe (r) showed distinctly two phalangeal divisions, the middle toe three, the outer the (b) four. And since, in living birds, the penultimate and ungual phalanges usually leave only a single impression, the inference was just, that the toes of this large foot had been characterized by the same progressively-increasing number of phalanges, from the inner to the outer one, as in birds. And, as in birds also, the toe with the greatest number of joints was not the longest ; it measured, e. g., 12i inches, the middle toe from the same base line measured 16 inches, the outer toe 12 inches. Some of the impressions of this huge tridactylous footstep were so well preserved as to demonstrate the papillose and striated character of the integument covering the cushions on the under side of the foot. Such a structure is very similar to that in the ostrich. The average extent of stride, as shown by the distance between the impressions, was between three and four feet ; the same limb was therefore carried out each step from six to seven feet forward in the ordinary rate of progression.
These footprints, although the largest that have been ob served on the Connecticut sandstones, are the most numerous. The gigantic Brcratozoum, as Principal Hitchcock proposes to term the species, "must have been," he writes, " the giant rulers of the valley. Their gregarious character appears from the fact, that at some localities we find parallel rows of tracks a few feet distance from one another." The strata of red sandstone, with the above-described im pressions, occupy an area more than 150 miles in length, and from 5 to 10 miles in breadth. " Having examined this series of rocks in many places, I feel satisfied that they were formed in shallow water, and for the most part near the shore ; and that some of the beds were from time to time raised above the level of the water and laid dry, while a newer series, composed of similar sediment, was forming." " The tracks have been found in more than twenty places, scattered through an extent of nearly 80 miles from N. to S., and they are repeated through a succession of beds attaining at some points a thickness of more than 1000 feet, which may have been thousands of years in forming."*
One of the evidences of birds from the Cambridge green sand, transmitted to the writer by their discoverer, Mr. Barret, B the lower half of the trifid metatarsal, showing the outer toe joint much higher than the other two, and projecting backwards above the middle joint ; it indicates a bird about the size of a woodcock.
In the conglomerate and plastic clay at the base of the eocene tertiary system at Mendon, near Paris, the leg and thigh bones (tibia and femur) of a bird (Gastornis Parisiensis) have been discovered : they indicate a genus now extinct. They belonged to a species as large as an ostrich, hut more robust, and with affinities to wading and aquatic birds.* In the eocene clay of Sheppy, fossil remains of birds have been found, indicating a small vulture (Lithornis vulturinas) ; also a bird, probably of the king-fisher family (Haleyornis toliapicu9), and a species of the sea-gull family. In the same formation at Highgate, remains of a species of the heron family have been found.
The fossil bones of birds from the gypsum quarries at Montmartre were referred or approximated by Cuvier to eleven distinct species. Good ornitholites have been obtained from the Hordwell fresh-water deposits.
The most ancient example of a passerine bird is the Pro tornis Glarisiensis, founded on an almost entire skeleton dis covered in the schistose rock of Glaris, referable to the older division of the eocene tertiary series. This skeleton is about the size of a lark, and in some respects similar to that bird.
Comparisons of the ornitholites of the eocene tertiaries show that the following ordinal modifications of the class of birds were at that period represented : the raptorial, or birds of prey, by species of the size of our ospreys, buzzards, and smaller falcons, and most probably also by an owl ; the insessorial, or tree-perching birds, by species seemingly allied to the nuthatch and the lark ; the seansorials or anisodactyles, by species as large as the cuckoo and king-fisher ; the rasorials, by a species of small quail ; the cursorials, by a species as large as, but with thicker legs than, an ostrich ; the grallatorial, by a curlew of the size of the ibis, and by species allied to Scotapax, Tringa, and Pelidna, of the size of our woodcocks, lapwings, and sand erlings ; and the natatorial, by species allied to the cormorant, but one of them of larger size, though less than a pelican ; also by a species akin to the divers (Merganser).
The remains of birds become more abundant and varied as we approach the present time ; especially in the miocene strata, so richly developed in France, although wanting in Britain. One of the most singularly-modified forms of beak is shown by the flamingo. The fossil skull of a species of this genus (Phcenicopterus) has been found in the miocene fresh-water deposits of the plateau of Gergovia, near Clermonte-Ferrand ; the entire metatarsal bone of a species of eagle (Aquila) or os prey (Panclion) in the same deposits at Chaptusal, Allier ; and the humerus of a bird allied to and as large as the albatross, in the molasse coquilliere marine at Armagne. Remains of a vulture, most probably a Cathartes, have been found in the miocene lacustrine deposits of Cantal. Indications of all the other orders of birds, save the great Cursores or Struthionidcc, have also been discovered in miocene strata—those of wading birds being the most numerous.