﻿216 ILLUSTRATIONS OF FOSSIL FOOTPRINTS 



divergence of the toes is so slight that they are in contact. There is a peculiarity in the 

 long toe which I shall show in other examples, namely, there appear to be but three 

 joints, yet it really has the requisite number ; the third and fourth joints being so com- 

 pressed as to form a single impression. The nails are strong and blunt, the tarsus deep 

 and apparently joined to the outer toe, and, on the whole, the foot is analogous to that of 

 struthioid birds. It may be noticed that the second and third joints of the central toe 

 brushed the stratum a little distance to the right, before the foot settled permanently. 

 As I shall have occasion again to refer to this beautiful example, I will now only say 

 that the stride is ten inches. 



Plate IV. 



The footprints upon this plate represent three distinct species of birds, and, from their 

 magnitude and perfect impress, they are peculiarly adapted to illustrate the organic 

 configuration of the foot. The originals were derived from Turner's Falls. 



Fig. 2 is the right foot of a short-legged, heavy bird, as is known by the shortness 

 of stride, which is fourteen inches, from the depth of the impression, and the breadth to 

 which the feet are separated. It is common at Turner's Falls, and a few other localities, 

 and is nearly always perfect. It is represented in consecutive series upon Plate I., the 

 lines of large impressions running from side to side representing this species. Fig. 2 

 is taken from a footstep in one of these lines. The toes are very massive, distinctly 

 separated, and the ungual appendages perfectly defined. The surface of the slab is not 

 rough, nor yet smooth, yet the weight of the bird condensed the resisting medium to the 

 smoothness of glass. The outer toe is relatively long and tapering, and the whole num- 

 ber shows the lobate divisions beautifully. In this instance, the tarsus did not descend 

 low enough to make a distinct impression, which is usually the case in this species. The 

 nails are blunt, long, and broad. Altogether, it is a most remarkable impression ; but 

 beyond the legitimate inference that it is referable to a heavy bird with short legs, all is 

 hypothetical. 



Connected Avith this species are the usual embarrassing questions concerning specific 

 distinctions. It is the representative of a large group of similar impressions, and is the 

 largest of the series. But, gradually descending in magnitude and extent of stride, are 

 many impressions that sustain a close affinity to it, and the question whether they should 

 be regarded as specifically different, or as being due to younger individuals, is difficult to 

 decide. If all the modifications of the fossil footprints were regarded as specific, the list 

 of species would indeed be very great. 



Fig 1. A right foot, in the general appearance analogous to Fig. 2, except that it is 



