12 Sir R. I. Murchison’s Address on the 
Cromarty, these fish-beds appear very near the base. But by 
following them into Caithness and the Orkneys, I have shown 
that they occupy a middle position, whilst the true base of the 
group is the equivalent of the zone with Cephalaspis, Pteraspis, 
and Pterygotus. 
And here it is right to state, that the Upper Silurian rocks 
which are clearly represented in Edinburghshire, and which in 
Lanarkshire seem to graduate upwards into the Lower Old Red 
or Cephalaspis sandstone, are wanting in the Highlands; thus 
accounting for the great break which there occurs between the 
erystallized rocks of Lower Silurian age and the bottom beds of 
the Old Red Sandstone. 
Of the Old Red Sandstone of Scotland and Herefordshire I 
may be permitted further to observe, that its downward passage 
into the uppermost Silurian rock, and the upward passage of its 
higher strata into the Carboniferous strata has been well devel- 
oped, the one near Ludlow, chiefly through the labors of Mr. 
Lightbody ; the other in Scotland, through the researches of the 
Government Geologists, Howell and eikis, as well as by those 
of Mr. D. Page and other observers, On this head I may, how- 
ever, note, what my contemporaries seem now to admit, that the — 
removal of the Caithness flags and their numerous included ich- 
thyolites from the bottom of this group, and their translation to 
the central part of the system, as first proposed by myself, is 
correct. In truth the lower member of this system is now un- 
equivocally proved to be the band with Cephalaspis, Pteraspis, 
&e., as seen in Scotland, England, and Russia. The great break 
which has been traced in the south of Scotland by Mr. Geikie 
between the lower and upper Old Red is thus in perfect harmony 
with the zoological fact that the central or Caithness fauna is en- — 
tirely wanting in that region, as in England—as it is indeed in ~ 
Ireland, where a similar break occurs 
It gratifies me to add that many new forms of those fossil 
fishes which so peculiarly characterize the Old Red Sandstones 
have been admirably described by Sir Philip de Grey Egerton 
in the Memoirs of the Geological Survey; and I must remark 
that it is most fortunate that the eminent Agassiz is here so well 
represented by my distinguished friend, who stands unquestion- 
ably at the head of the fossil ichthyologists of our country. 
Very considerable advances have been made in the deyelop- 
ment of our acquaintance with that system—the Carboniferous— 
which in the north of England (Yorkshire) has been so well de- 
scribed by Professor Phillips, and with which all practical geol- 
ogists in and around Manchester are necessarily most interested. 
‘he close researches of Mr. Binney, who has, from time to time, — 
thrown new lights on the origin and relations of coal, and the 
component parts of its matrix, established proofs, so long ago — 
