Obscure Markings upon an Old Red Sandstone. 163 
The communications read were as follows : — 
I. On some Obscure Marldngs upon an Old Red Sandstone Slab at 
Mill of Ash, near Dunblane. Bj the Rev. Robert Hunter, late of 
Nagpore. 
The large slab, half of which has been laid upon the table, 
is a micaceous flagstone, from a fissile layer, a few inches thick, 
with a more compact sandstone or gritstone both above and 
below it, and at no great distance from a trappean effusion. 
It would seem to belong to the lowest or Cephalaspis zone 
of the Old Red Sandstone. The Rev. Walter Smith, of Free 
Roxburgh Church, in this city, when with me last August, in 
a quarry at Mill of Ash, observed some of the markings on a 
projecting ledge of stone, and that day and the next he and I 
laid the rock bare for a space of six feet in length by five in 
breadth, and came on about 150 of the markings. More 
recently, the slab was raised, and the Rev. Mr Paterson, of 
Dunblane, kindly consented to take the trouble of having it 
packed and forwarded to Edinburgh. The impressions are of 
two sizes. Their form is elliptical, with a raised border, one 
side being in much bolder relief than the other ; and it is im- 
portant to note that the raised margins all correspond in posi- 
tion with each other. Within, and separated from the elevated 
border by a channel, there is occasionally a raised central 
space, with a tendency to longitudinal furrowing. The longer 
axes of the ellipses all point nearly in the same direction. 
They are arranged with some regularity, though at times two 
are in such close contact as to form an eight figure, and, more 
rarely, a couple of these eights uniting have constituted a rude 
cross. Mr Page possesses some curious impressions from 
Ardoch. a few miles north of Mill of Ash, but judging from 
some figures he hastily drew for comparison, they are of forms 
entirely different from those now described. It is difficult to 
say whether the markings are of organic or inorganic origin. 
The hypothesis on the subject which most naturally arises, 
and being expelled has a tendency to return, is, that they are 
footprints of some animal. There are, however, very formidable 
objections to this view. Nor can they well have been formed 
by pebbles, or by the impressions of ganoid scales, for sub- 
