436 
THE GEOLOGIST. 
been for some years endeavouring to establish as to the true position of the 
Caithness flags with their numerous ichthyohtes seems to be admitted by my 
contemporaries. The lamented Hugh Miller considered these ichthyolites 
as belonging to the lower member of the group, and had good grounds for his 
views, since at his native place, 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 betweeu 
the crystallized rocks of Lower Silurian age and the bottom beds of the Old 
Eed Sandstone. 
Of the Old Red Sandstone of Scotland and Herefordshire I may be permitted 
further to observe, that its dowiward passage into the uppermost Silurian 
rock, and the upward passage of its higher strata into the Carboniferous strata, 
has been well developed, the one near Ludlow, chiefly through the labours of 
Mr. Lightbody ; the other in Scotland, through the researches of the Govern- 
ment Geologists, Howell and Geikie, as well as by those of Mr. D. Page, and 
other observers. On this head I may, however, note, what my contemporaries 
seem now to admit, that the removal of the Caithness flags and their numerous 
included ichthyolites 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 unequivocally proved to be the' 
band with Cephalaspis, Pteraspis, &c., 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 entirely 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 Sandstone, have been admirably describedi 
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 unquestionably at the; 
head of the fossil ichthyologists of our country. i 
Very considerable advances have been made in the development of our ac- 
quaintance with that system — the Carboniferous— which in the North of England 
— Yorkshire — has been so well described by Professor PhiUips, and with which 
all practical geologists in and around Manchester are necessarily most interested. 
The 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 as 1840, that great part of our coal-fields was 
accumulated under marine conditions ; the fossils associated with the coal-beds 
being, not as had been too generally supposed, of fluviatile or lacustrine cha- 
racter, but the spoils of marine life. Professor Henry Rogers came to the same 
conclusion with regard to the Appalachian coal-fields in America, in 1842., 
Mr. Binney believes that the plant Sigillaria grew in salt water, and it is to be 
remarked that even in the so-called " fresh-water limestones" of Ardwick and 
Le Botwood, the Spirorbis and other marine shells are frequent, whilst many of 
the shells termed Cypris may prove to be species of Cythere. Again, in the 
illustrations of the fossils which occur in the bands of iron ore in the South 
Welsh coal-field, Mr. Salter, entering particularly into this question, has shown 
that in the so-called " Unio beds" there constantly occurs a shell related to the 
Mya of our coasts, which he terms Anthracomya ; whilst, as he has stated in 
