AND THE ADJOINING DISTRICT, BERWICKSHIRE. 35 
Organic remains were first discovered among these sandstones, in the summer 
of 1840, in a fine section exposed by the Whiteadder about half a mile below Cock- 
burn Mill. These chiefly consist of scales, occipital plates, ichthyodorulites, and 
other bony parts of the Holoptychius Nobilissimus. Similar remains also occur in 
the sandstones directly opposite to Cockburn Mill, and in those to the east of the 
Knock hill. They are not distributed uniformly through the strata in which they 
occur, but are found only in particular beds, in which they abound; while very 
few or none are to be seen in the adjoining strata. At Cockburn Mill, the ichthy- 
olitic beds are situated within a hundred feet of the conglomerate, from which 
they are separated by a series of intervening beds of unfossiliferous red sand- 
stones, and thin strata of conglomerate. One bed which is exposed here contains 
the remains of the Holoptychius in such abundance, that a chip cannot be struck 
off without disclosing a portion of a scale or plate. «It is of a coarse, sandy, gritty 
texture, and is generally so brittle from being highly impregnated with animal 
matter, as to be easily broken between the fingers. It is only a few inches thick. 
Some of the thicker beds with which it is associated also contain these fossils in 
considerable abundance, but they appear to be in greater quantity near the surfaces 
of each stratum, few being found in the interior of a thick bed. These strata pre- 
sent beautifully rippled surfaces, and (especially the gritty bed above mentioned) 
shew other unequivocal marks of littoral deposition. A circumstance which tends 
strongly to favour the view of their having been formed near the shore, is the fact 
of their included remains being of such a fragmentary character, that although 
pieces of scales and plates may be picked up in hundreds, it is very rare to find 
one of either that is not more or less mutilated. Indeed, it would appear that after 
those large fishes died, their osseous parts, being separated by decomposition and 
the action of the waves, were tossed about on the sandy beach, and exposed to at- 
trition among the coarse sand and pebbles, until they were reduced to the frag- 
mentary state in which we now find them. The fact of the remains of the Holop- 
tychius being chiefly found associated with appearances indicative of the proximity 
of the shore, would almost lead one to suppose that these fishes were in the habit 
of frequenting shallow water, perhaps because of their food being there more abun- 
dant. At all events, their remains appear to be confined to these rippled strata; for 
in the corresponding beds of the old red sandstone above Greenlaw, which are des- 
titute of ripple marks, and bear evidence of having been deposited in deep water, 
there are no traces of them to be found. 
On the east side of the Knock hill, the ichthyolitic beds of this formation are 
tilted up at high angles by the mass of grey porphyry of which that hill consists. 
The remains found here are of the same fragmentary character as those of Preston- 
haugh, and abound most in a few thin sandy beds within a few feet of the por- 
phyry. They consist chiefly of the scales, plates, spines, and teeth of a fish allied to 
the Holoptychius, but differing from it in several particulars, the scales being more 
