THE FOSSIL FOOTMARKS OF THE UNITED STATES. 163 



pression that gives any evidence of quadrupedal origin, save in the 

 number of the toes ; which, indeed, in living animals, is a good 

 criterion for the most part. But we shall see in the sequel that 

 some quadrupeds have lived with only three toes (at least on the 

 fore feet) directed forward, and some bipeds with at least four 

 toes directed forward (e. g. the Macropterna and Otozoum) ; so 

 that the number of toes is a somewhat equivocal character. 



There are some quadrupedal animals, whose tracks would be 

 arranged in two rows; not, as first described, with two approximate 

 tracks succeeded by a wide interval, but probably, for the most 

 part, equidistant. The extreme tracks on Plate 19, fig. 3 (that is, 

 those at the ends of the rows), were copied from the feet of the 

 banded Proteus (Menobranchus lateralis), sent to me alive, in April, 

 1848, by Rev. J. W. Ray, from Oswego, N. Y., where it was caught 

 in the autumn of 1847. The sketches were obtained by placing the 

 animal, soon after death, in a natural position, such as I had often 

 seen it assume when alive. They are shown on the plate of the 

 natural size. Now as this animal's legs are not more than an inch 

 or two long, it is clear that in walking he could not bring up the 

 hind foot half way to the fore one, but might be expected to leave 

 its tracks somewhat as represented by the dotted impressions on the 

 plate, though probably they would not be as nearly equidistant as 

 the sketches are. It is plain, however, that such an animal would 

 leave two rows of tracks, not alternating, nor arranged as in fig. 1 

 of the same plate. Among the fossil footmarks, we have an anal- 

 ogous case in the tracks of Macropterna divaricans (leaving out the 

 fore feet), as is shown on Plate 19, fig. 5 ; and also, more exactly, 

 in Ancyropus heteroclitus, shown on Plate 19, fig. 4. 



The angle made by the line of direction and the axis of the 

 feet, as well as the distance of the feet laterally from that line, are 



