——— 
= = as 
‘i 
TRANSACTIONS OF THE SECTIONS. 83 
‘Caithness flags of the east coast, and Prof. Nicol having since suggested that they were 
ossibly of carboniferous age, or the equivalents of the sandstones and carboniferous 
ore of the South of Scotland (Quart. Journ. Geol. Soc. vol. xiii. p. 36), it is 
essential that my own view should be explained to the British Association, before 
which body the subject has already undergone discussion. 
‘The annexed Note demonstrates, that the fossil shells last collected by Mr. Peach, 
and which he sent to me, are forms which characterize one of the lowest zones of 
the Silurian rocks of North America; and therefore the paleontological evidence is 
in accordance with that of the physical geologist. 
I would here observe, that in tracing the Silurian rocks to the north and west, we 
begin to find North American types which are unknown to us in the Silurian region 
or in any part of England and Wales. Thus, in the South of Scotland, the Maclurea 
magna (Hall) is a well-known Ayrshire fossil, and in Ireland the Isotelus gigas 
(Dekay) is not unfrequent, and these are species which do not range further south- 
ward or eastward. [tis therefore peculiarly interesting to find in a still more northern 
tract, a zone which is as low in the series of metamorphosed rocks in which it occurs, 
as the Canadian and North American calciferous sand-rock is in the regular and un- 
altered deposits of those countries. 
__ As this notice is to be read at the Dublin Meeting, I venture to recall the attention 
of my Associates to the hypothesis which I put forth in my work, ‘ Siluria’ (1854), 
viz. that the quartz rocks, micaceous schists and marbles, grey and green, of the 
Bins of Connemara in Galway, are also nothing more than metamorphosed ‘ Lower 
Silurians.’ It is true, that no organic remains have yet been detected in any portion 
of these rocks, though perchance, if their weathered surfaces were searched by as keen- 
eyed a collector as Mr. Peach, they might afford such evidences. 
My belief is founded on the fact, that the fossils found near Leenane, Maam, and 
_ other places, are none of them of higher antiquity than the Llandovery rocks (Middle 
Silurian), and merely indicate a passage downwards; so that the crystalline rocks 
which dip regularly beneath these fossil-bearing rocks may well represent the Caradoc 
or Bala formation, and the Llandeilo and Lingula flags, in a metamorphosed condition. 
Note on the Fossils from Durness. By J. W. Sarter, F.G.S. 
Tt had given no little trouble, which had yet no satisfactory result, to examine and 
decide upon the fragments formerly collected in these altered limestones. There 
were always some reasons for regarding them as Lower Silurian forms, although the 
first reference of any of them to that period was only made with a wide margin for 
doubt. And so like were some fragments to those of chambered shells, and even 
Goniatites, that it was impossible quite to rebut Professor Nicol’s notion that the whole 
might prove of carboniferous age, though the grounds on which he stated that belief 
(the presence of Stigmaria for instance) were far from satisfactory. Quart. Geol. 
Journ. vol. xiii. p. 36. 
Mr. Peach’s specimens, however, furnish us with a fortunate coincidence with 
some of the yet unpublished fossils of Canada, for a knowledge of which we are 
indebted to Sir W. Logan’s zeal in bringing over his whole collection to England for 
purposes of comparison. (See Quart. Geol. Journ. vol. viii. p. 201.) In Canada, the 
rock which immediately overlies the Potsdam sandstone, viz. the calciferous sand- 
rock, contains only a few fossils, but these are characteristic of the horizon. Among 
them is a genus or subgenus allied to the Raphistoma of Hall, which has received the 
name Ophileta from Vanuxem, and consists of species which have a very wide open 
umbilicus angular at the edge, and with straight sides to the whorls. 
n Durness the same genera and even species has been found. The Canadian speci- 
mens are far larger than the British ones, but show the same characters, and the name 
Ophileta compacia hasbeen applied to them in MSS. and will be published in the Deca’ 
of the Canadian Survey. With them, in Canada, occurs a peculiar Euomphalus, or 
some such genus, to which the term Maclurea matutina is applied by Hall. And I 
cannot distinguish certain flattened spiral shells (with the same proportions) in the 
Scotch collection, from these. Again, there is a Plewrotomaria very like the P. subco- 
nica, Hall, from the Trenton limestone. ‘The Scotch fossil resembles it in shape and 
in the position of the band, but has narrower whorls. Another Trenton limestone 
6* 
