ORNITHYCHNOLOGY. 



721 



biped in progression forward. The interval, also, he- ' 

 tween the different steps varies ; sometimes several | 

 inches in the smaller impressions, and even a foot 

 or two in the larger; just as much, indeed, as we 

 should expect in an animal moving at different paces: 

 and where the impressions are distinct, it is easy to 

 determine whether it were made by the right or 

 left foot of the animal. This can be decided even 

 in insulated foot-prints. Sometimes different 

 species of animals, and different individuals, have 

 crossed one another's tracks so often, that all is 

 confusion ; the whole surface being trodden over, 

 as we often see to be the case where quadrupeds 

 or ducks and geese resort, upon the muddy shores 

 of a stream or pond. In short, there cannot 

 remain a doubt but these impressions are the 

 tracks of birds, made While the incipient sandstone 

 and shale were in a plastic state. That they are 

 the foot-prints of birds, the following arguments 

 go to prove: 



1. These impressions are evidently the tracks of 

 a biped animal ; for in no instance has there been 

 discovered the existence of more than a single row 

 of impressions. 2. They could not have been 

 made by any other known biped, except birds. 

 3. They correspond well with the tracks of birds ; 

 having the same ternary division of their anterior 

 part as the feet of birds. Frequently, and per- 

 haps always, the toes, like those of birds, are ter- 

 minated by claws. If the toes are sometimes 

 slender, and sometimes thick and blunt, so are 

 those of birds. If the hind toe or hollux is mostly 

 wanting in these impressions, so are the feet of 

 many genera of birds, especially the grallae or 

 waders. 



The accompanying figure re- 

 presents recent impressions in 

 mud, of the Canada goose (Anas 

 Canadensis). The length of the 

 foot is four inches, and of the 

 step seven inches. The space 

 beneath the web connecting the 

 toes, is quite obvious on the 

 mud ; it being sunk below the 

 general level, but not so deep 

 as the toes. The entire absence of any such ap- 

 pearance in the fossil tracks, makes it almost cer- 

 tain, that none of them were produced by web- 

 footed birds. 



All the varieties of tracts hitherto discovered, 

 may be included under two divisions: 1. The 

 Pachydactyle, or thick toed ; 2. The Septodactyli, 

 or slender toed. 



DIVISION I PACHYDACTYLE. Hitchcock. 



The toes of almost equal thickness through 

 their whole extent, except that they are tuberous, 

 and terminate rather abruptly; and usually with a 

 pointed claw. 



1. Ornithicnites giganteus. Toes, 

 three, directed forward ; length of the 

 foot, fifteen inches, exclusive of the 

 claws; claw about two inches in 

 length; total length of the foot from 

 sixteen to seventeen inches 1 Length 

 of the successive steps, from four to six 

 feet! Toes somewhat tuberculated ; 

 inner one, in some specimens, distinctly exhibiting 

 two protuberances, and the middle one three, less 

 distinct; average thickness of the toes, one inch and 

 a fourth; breadth of ditto, two inches. Average 

 step supposed to be four feet. 



From the length of step, the bird must have 



VII. 



been twice the size of an ostrich, and its head 

 elevated twelve to fifteen feet above the ground. 

 The length of leg of the African ostrich is about 

 four feet, and that of its foot ten inches. 



Found only at Northampton, east side of Mount 

 Tour, where it is abundant. In one place, there 

 appeared the tracks of four individuals, pointing in 

 one direction, from which it is inferred, that this 

 species was gregareous. 



2. O. Tuberosus. TOPS, three directed 

 forward, each provided with a claw, from 

 one inch to one and a half inches long ; 

 with tuberous swellings on the under side, 

 quite distinct ; heel very obvious, with 

 three prominences in the middle toe, and 

 two on the others; length of the foot, seven or 

 eight inches. Length of step from twenty-four to 

 thirty-three inches. Found at Northampton ; and 

 also at Horse Race, in Gill. 



The most important difference between this 

 and the O. giganteus, consists in its smaller size. 

 It might be supposed the young of that species ; 

 but no intermediate sizes have been noticed ; 

 besides the middle toe of the former is larger in 

 proportion to that of the others, than in the latter 

 species, and the toes of the latter are considerably 

 more divaricate than the former. 



3. O. Dubius. Resembling in its general appear 

 ance the O. tuberosus, but much smaller, the foot 

 being only four inches long, and the steps twelve 

 inches ; probably a distinct species, but uncertain, 



DIVISION II. SEPTODACTYLE. 

 Toes much narrower, and less than in the first 

 division. Some are very slender; they taper 

 gradually to a point, and the claws not often dis- 

 tinctly perceptible. 



1. O. Ingens. Three toes, no visi- 

 ble claw on any specimen yet discov- 

 ered, toes narrow, tapering gradually 

 to a somewhat obtuse point; quite 

 divaricate ; at a few inches behind the 

 heel there is a depression nearly an 

 inch deep, and several inches across ; 

 the anterior slopes to which in the 

 rear, appear as if large bristles had 

 been impressed upon the mud. It 

 would seem that the bird possessed a 

 kind of knobbed heel, covered with 

 hairy feathers, which sunk into the 

 mud when the track was deep ; impressions of the 

 bristles extending backwards from the heel, from 

 eight to nine inches, producing in all an impression 

 not less than two feet ! Length of the foot, ex- 

 clusive of the hairy appendages, fifteen or sixteen 

 inches. The ordinary step appears to have been 

 about six feet! Found only at Horse Race. 



. The rock on which the foot prints of this spe- 

 cies occur is composed of a fine blue mud, such as 

 is now common in ponds and estuaries ; and where 

 the bird trod upon it, in some cases, it seems that 

 the mud was pressed upwards, forming a ridge 

 around the track in front; and so deep is the im- 

 pression, that it would require nearly the weight 

 of an elephant to produce one of equal depth. 



2. O. Ingens, variety minor. Length of the 

 foot about twelve inches ; step from forty to 

 forty-five inches ; agreeing in other respects with 

 the O. Ingens. 



3. O. Diversus. Three-toed, with a hairy ap- 

 pendage in the rear; length of foot, independent 

 of the appendage, from two to six inches ; length 

 of step from eight to twenty-one inches. 



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