116 ON THE STAGONOLEPIS ROBERTSONI AND THE 
This impression (fig. §) measures about 2} inches transversely, and 
longitudinally 2} inches, or a little less. 
The planter surface measures 1 inch from before backwards, and 
its posterior edge is nearly semicircular and not emarginated. The 
anterior edge is nearly straight. It gives off four deepish longi- 
tudinal impressions, answering to as many digits. Of these the 
middle two measure 14 inch in length, and are consequently some- 
what longer than the inner and the outer, which are hardly more 
than } inch long. 
The ungual phalanges appear not to have attained a length of 
&ths of an inch in the longest digits, and all four digits appear to 
have been connected by a web. The anterior and external angle 
of the plantar surface projects 2ths of an inch beyond the base of 
the fourth digit, as if there had been a rudimentary fifth digit. 
The length of the stride, from the hinder edge of one fore-foot 
print to that of the next, is just twelve inches. The space covered 
by the track transversely to its length, measured from the outer edge 
of one footmark to a line prolonging that of the footmark on the 
opposite side, is about ten inches. 
On the same slab as that on which these tracks occur there are a 
number of other footmarks, some of which are nearly eight inches 
long, while others hardly exceed an inch in length. They are all, 
however, more or less imperfect, either from the condition of the 
surface at the time they were impressed, or from the subsequent 
superposition of other impressions. The only feature which they 
exhibit better than those just described is the mark of the inter- 
digital membrane, which in some of these footmarks is very obvious, 
and exhibits strong transverse wrinkles, concave forwards. 
All the other foottracks from Cummingstone which have come 
under my notice are either mere unintelligible marks, or may be 
explained by the perfect footsteps I have just described ; so that at 
present I see no reason for believing that the tracks were caused by 
more than one species of Reptile. The great apparent differences 
between some of these footmarks and others appear to be referable 
to the varying condition of the sand upon which the tracks were 
made. 
In the length of the impressions made by the ungual phalanges, 
and in the large size of the anterior as compared with the posterior 
foot, the Cummingstone tracks are, so far as I know, unlike those of 
any known Crocodilian or Chelonian (?) reptile ; but it must be con- 
fessed that there is a great want of recent materials in attempting to 
study comparative ichnology. The footmarks in question are not 
