neighborhood of the town of Thurso,
about half a mile to the east of the river, is not a little curious.
Bearing throughout the general dingy hue of the flagstones, they yet
consist of alternating beds of two distinct characters and qualities.
The one kind, fissile, finely grained, and sharply ripple-marked, seems
to have been deposited in shallow water; the other, not fissile, but, if
I may so speak, felted together so as to yield with difficulty to the
hammer in any direction, and traversed by polygonal partings, filled up
usually by the substance of the overlying stratum, appears to have had a
different origin. The state of keeping, too, in which the ichthyic
remains of these alternating beds occur is always very different. The
smaller and more delicately organized fishes are never found entire,
save in the fissile, finely grained beds; in the others we detect only
scattered fragments; and even these, unless they belonged to the robust
Asterolepis or his congeners,--which, however, in these beds they
usually do,--much broken. The polygonal partings seem to indicate that
these toughly-felted beds, whose very style of weathering--rough,
gnarled, fretted into globose protuberances and irregular hollows--shows
that it had not been formed by quiet deposition, must have had their
broad backs raised for a time above the surface of the water, to be
desiccated in the hot sun. And the fragmentary state of the fossils
which they contain seems to point, with the roughnesses of their
weathered surfaces, to some peculiarity in their origin. The
recollection which they awoke in my mind with each visit I paid them for
three years together, may probably indicate what that origin was. I had
a relation who died more than a quarter of a century ago, who passed
many years in British Guiana, in the colony of Berbice, and whose
graphic descriptions of that part of South America made a strong
impression upon me when a boy, and still dwells in my memory. He was
settled on a cotton plantation near the coast side; and so exceedingly
flat was the surrounding country, that the house in which he dwelt,
though nearly two miles distant from the shore, stood little more than
five feet above its level. The soil consisted of a dark gray
consolidated mud; and in looking seawards from the margin of the land,
there was nothing to be seen, when the tide fell, save dreary mud flats
whole miles in extent, with the line of blue water beyond stretching
along