LAND TORTOISES. 259 
restrial reptiles, during the period of the New 
red, or Variegated sandstone formation. (See 
PI. 1, Sec. 17). The nature of this evidence 
is almost unique in the history of organic 
remains.* 
It is not uncommon to find on the surface of 
sandstone, tracks which mark the passage of 
small Crustacea and other marine animals, whilst 
* See Dr. Duncan's account of tracks and footmarks of ani- 
mals, impressed on sandstone in the quarry of Corn Cockle Muir, 
Dumfries-shire, Trans. Royal Society of Edinburgh, 1828. 
Dr. Duncan states that the strata which bear these impres- 
sions lie on each other like volumes on the shelf of a library, when 
all inclining to one side : that the quarry has been worked to the 
depth of forty-five feet from the top of the rock ; throughout the 
whole of this depth similar impressions have been found, not on 
a single stratum only, but on many successive strata; i. e. after 
removing a large slab which contained foot-prints, they found 
perhaps the very next stratum at the distance of a few feet, or it 
might be less than an inch, exhibiting a similar phenomenon. 
Hence it follows that the process by which the impressions were 
made on the sand, and subsequently buried, was repeated at 
successive intervals. 
I learn, by a letter from Dr. Duncan, dated October, 1834, 
that similar impressions, attended by nearly the same circum- 
stances, have recently been discovered about ten miles south of 
Corn Cockle Muir, in the Red sandstone quarries of Craigs, two 
miles east of the town of Dumfries. The incHnation of the 
strata of this place is about 45° S.W. like that of almost all the 
sandstone strata of the neighbourhood. One of these tracks 
extended from twenty to thirty feet in length ; in this place also, 
as at Corn Cockle Muir, no bones of any kind have yet been 
discovered. 
Sir William Jardine has informed Dr. Duncan that tracks of 
animals have been found also in other quarries near Corn Cockle 
Muir. 
