FOOTMARKS IN THE SANDSTONES OF CUMMINGSTONE 107 
ventral shield of the Zeleosaurta, the bread and the thick angulated 
scutes to the dorsal scutes of the same Crocodilians, while the zrregaular 
angulated scutes are very similar to the dermal bones, which are 
scattered between the margins of the dorsal and cervical shields of 
the existing Crocodiles. 
At this stage of the inquiry, the full meaning of a piece of 
evidence, whose value I had, up till then, but very imperfectly recog- 
nized, became obvious. This was a remarkable natural cast, obtained 
by Mr. Patrick Duff, at Findrassie, and which had been sawn through 
longitudinally by that gentleman’s direction, so as to expose its 
internal conformation. At first sight this curious fossil resembled 
nothing so much as the crushed and distorted cast of an Orthoceras, 
but koth Mr. Duff and Sir Roderick Murchison had suspicions of its. 
real nature, and in fact it turns out to be one of the most singular 
organic remains ever discovered, consisting of a natural cast of both 
the dermal bones and the vertebre of a considerable segment of the 
tail. 
Loaded by its heavy dermal plates, this caudal fragment appears 
to have sunk into the fine siliceous mud, the accumulation of which 
has given rise to the Findrassie sandstone, and to have been com- 
pletely permeated therewith, all the cavities left vacant by the 
putrefaction of the soft parts becoming filled up with a substance 
which soon hardened into stone. After this had taken place, the 
bony matter was, by some agency or other (probably the percolation 
of water;, completely removed, so that the fossil, which must have 
originally lain loose in a natural mould of the outer surfaces of the 
caudal scutes (which has unfortunately not been preserved), exhibits,. 
externally, a complete cast of the inner surfaces of a number of suc- 
cessive transverse series of scutes, and, internally, the casts of the 
outer surfaces and neural canals of a corresponding number of caudal 
vertebree. 
The impressions of the dorsal scutes are but little disturbed, and 
it is at once obvious that they belonged to the kind which I have 
named above broad angulated scutes. They form a double series. 
along the dorsal region of the tail, and their inner edges meet along 
a median sutural line. 
The ventral scutes also appear to have formed only a double 
series, meeting in the middle line; but they are much more dis- 
placed, the left-hand set being particularly thrown out of position. 
These scutes are nearly square, and perfectly flat, corresponding 
exactly in form with the fla¢ scutes already described. It would 
appear that in the caudal region (as was probably the case in the 
