Vol. 62.] FOOTPRINTS FROM THE FERMIAN OF MA.NSFIELD. 129 



an idea which might seem to receive considerable support from the 

 out-turned fifth digit. On more careful examination, however, the 

 supposititious association has to be abandoned. Cheirotheroid prints 

 have the following characteristics : — Of the five digits, ir, in, and iv 

 are stout and strongly marked, the fifth is set back and curves out- 

 wards and backwards, while the first is much less conspicuous and 

 quite commonly leaves no impression. There is never any trace of a 

 heel, except in the aberrant Cheirotherium Herculls, and in some cases 

 impressions of the digits alone are seen. There is no trace of any 

 interdigital membrane. The stride was long, commonly about a 

 yard, and all the impressions are nearly in one line, indicating an 

 animal very well adapted for rapid progression on land. The fore feet 

 were greatly reduced, and nearly the whole weight was supported 

 by the hind limbs. 



Very different are the characters of the impressions with 

 which we are concerned here. They were made by an animal 

 emphatically plantigrade. The stride was very short, and the gait 

 that of a clumsy animal ill-fitted for walking. The fore feet were 

 only a little smaller than the hind feet, and the weight of the body 

 was much more evenly distributed. The digits were comparatively 

 slender, and were probably joined by a web. Even the fifth digit, 

 though modified, was much less so than in Cheirotherium. In 

 passing, it may be remarked that this modification of the fifth digit 

 seems to have been a fairly-common feature among the animals of 

 Permian and Triassic times, and some explanation of its meaning 

 might be interesting. 



The only previously-described impressions that I have been able 

 to find, which do present any close resemblance to these Mansfield 

 prints, are those from the Upper Permian of Thuringia, of which an 

 account has been written by W. Pabst. 1 The footprints there described 

 under the name of Ichnium acrodactylum agree in a striking manner 

 with those here described. In size, in general form, in the arrange- 

 ment, of the digits, and in the general arrangement of the track no 

 decided distinction can be found. The individual prints, however, 

 differ markedly in one respect, namely, in the much greater stoutness 

 of the digits in the Thuringian form, so that between the first four 

 digits no marked interspaces appear. The digits are also somewhat 

 longer. To some extent, though not entirely, these differences may 

 be accounted for by the fact that the Thuringian prints are more 

 deeply impressed than the Mansfield prints. 



Two other points serve to distinguish definitely these two sets of 

 tracks : the first, that the difference in size between maims and pes 

 in Ichnium acrodactylum is still less marked than in our own prints; 

 the second, that the stride of the former is much longer — approxi- 

 mately 12 inches. The feet (at least, the hind feet) v were slightly 

 less than in the Mansfield form. Yet, despite such differences, the 

 general resemblance is so strong that one can scarcely do other 

 than suppose a real relationship between the Thuringian animals 

 and those of our own ancient shores. 



1 Zeitschr. d. Deutsch. Geol. Gesellsch. vol. xlix(1897) pp. 701 et seqq. 



