206 PROCEEDINGS OF THE GEOLOGICAL SOCIETY.  [Jan. 5, 
Asaphus tyrannus. A little differmg in the ribs of the tail. 
Phacops Odini, Kichwald. Lower Silurian ; or a Bala limestone 
species not yet published. 
Illenus Davisii® Lower Silurian. 
Cheirurus. Probably portions of the head. 
SHELLS. 
Iituites Cornu-arietis, Sow. The straight portion. 
Leptena tenuistriata, Sow., variety. 
Spirifer biforatus, Schlotheim, var. 
Orthis calligramma, Dalm. Abundant. 
, var. with numerous ribs. 
Orthis, broad species, very imperfect. 
Orbicula sp. 
oe 
ZOOPHYTES. 
Graptolithus Sedgwickii, Portlock. 
The aspect of this list is entirely Lower Silurian, and very much 
what might be found in the Llandeilo flags of Wales. The smooth 
Asaphi are only yet known in Lower Silurian rocks: and it is rather 
remarkable, as tending to connect this range of hills with the Lower 
Silurian rocks of Tyrone and Fermanagh, that they have only yet 
been described in Britain from those counties, and I do not know 
them elsewhere. The Graptolithus Sedgwick is also abundant in 
the same schists. Orthis calligramma swarms in the slates of Gal- 
way ; and species of I//enus and Cheirurus are abundant in Tyrone. 
Since these fossils were collected, a very interesting addition to 
the geology of the Lammermuir range has been made by Lord 
Selkirk in a collection of fossils from St. Mary’s Isle; they are m 
my opinion Upper Silurian :— 
Terebratula semisulcata, Leptena sarcinulata, Atrypa reticularis, 
Bellerophon trilobatus, Natica, Turritelle, Murchisonia, Avicula 
lineata, Orthonota cingulata, &c., Phacops caudatus, Beyrichia _ 
tuberculata, Graptolites Ludensis. These characteristic Upper Silu- 
rian fossils are accompanied by a Leptena sericea, and Orthoceras 
tenuicinctum of Portlock. On the whole they appear to be of the 
date of Wenlock shale.—J. W. Sater. 
In addition to these remarks of Mr. Salter only a few observations 
are necessary. Ist. The date of Lower Silurian, indicated by the 
fossils, would agree well with the high antiquity which, on wholly in- 
dependent grounds, I have assigned to this formation. At the same 
time, the number of species is so small, and the specimens so im- 
perfectly preserved, that we must still consider this identification as 
in some degree uncertain. On the whole, it is probably safer still to 
retain for these rocks the old name of Transition, or merely class 
them as Silurian, without attempting any more precise definition. 
This is the more necessary from the wide interval unoccupied by any 
deposits, which divides them from the next higher step in the geo-— 
logical series of formations. The red sandstone by which they are 
