TRANSACTIONS OF THE SECTIONS. 71 
portant bearing which it had on the general classification of the rocks between the top 
of the Silurian and the bottom of the carboniferous formations, usually classed as one 
thing under the terms of Old Red Sandstone, or Devonian Rocks. 
Along the extreme western coast, between Sibyl Head and Slea Head, a distance 
of six miles, a nearly continuous section may be seen, consisting chiefly of red and 
greenish slates, sandstones and conglomerates, all dipping to the south at an angle of 
about 60°, except the red sandstones and conglomerates of Sibyl Head, which dip to 
the north, and repose unconformably on other red sandstones and conglomerates, the 
age of which is doubtful. 
Between Ferriter’s Castle and Doonquin the rocks are full of Upper Silurian fossils, 
and contain interstratified beds of contemporaneous traps and ashes, principally feld~ 
spathic. By means of these peculiar beds, an inverted S-like contortion or anticlinal 
and synclinal curve may be traced about Clogher Head; and if we take a certain band 
of red sandstone and fine conglomerate interstratified with thin ash-beds as a boun- 
dary, the fossils found below are more peculiarly Wenlock species, while those above 
are Ludlow, including in some places an abundance of Pentamerus Knightii. 
The following fossils, as determined by Mr. Salter, occur in the lower or Wenlock 
group :— 
Zoophyta.—Favosites polymorpha, alveolaris; Leperditia balthica; Halysites catenu- 
latus; Alveolites De la Bechei; Syringopora ramulosa; Omphyma turbinatum. 
Brachiopoda.—Strophomena depressa, euglypha, compressa, pecten; Athyris tumida; 
Rhynchonella nucula, navicula; Orthis elegantula, caligramma, rustica; Spirifer 
trapezoidalis, bijugosus ; Atrypa reticularis. 
Conchifera.—Pterinza retroflexa, orbicularis, planulata, &c.; Avicula lineata; Gram- 
myria cingulata, &e. 
Gastcropoda.—Euomphalus funatus, alatus, lautus; Acroculia Haliotis; Murchisonia 
articulata?. 
Crustacea.—Calymene Blumenbachii ; Lichas anglicus, Barrandii; Encrinurus punes 
tatus. 
In the Upper or Ludlow group, the following species occur according to the same 
authority :— 
Zoophyta.—Favosites multiporata, alveolaris; Heliolites interstinetus, var. Megas- 
toma; Stenopora fibrosa ; Syringopora filiformis. 
Brachiopoda.—Rhynchonella Wilsoni, navicula; Orthis filosa, elegantula; Atrypa 
reticularis; Athyris tumida; Spirifer elevatus ; Strophomena filosa; Pentamerus 
Knightii, galeatus. 
Conchifera.—Avicula reticulata; Pterinza rectangularis; Orthonota rigida; Gonio- 
phora eymbzeformis. 
Gasteropoda,—Euomphalus funatus. 
Crustacea.—Phacops caudatus. 
This Upper or Ludlow band strikes from Doonquin into the interior, forming the 
hill of Croaghmarin, and the adjacent ground.- Over it may be scen a set of red 
shales and sandstones 800 or 1000 feet thick, which may be considered as passage 
beds from the Ludlow into the overlying rocks, and thus representing the Tilestones 
of South Wales. ‘These pass gradually upwards into a great mass of pale green and 
dull purple grits and slates, which, in conjunction with Mr. Griffith, the authors call 
the Glengariff grits. These beds are about 6000 feet thick; they contain no fossils, 
but have occasional calcareous bands like the Cornstones of South Wales and Here- 
ford, and are believed to be contemporaneous with the Cornstone group of the Old 
Red Sandstone of that district. 
Above the Glengariff grits come a nearly equally thick series of bright red slates 
and sandstones, with thick beds of coarse conglomerate. containing pebbles of calca- 
reous grit which have fossils belonging to the Llandovery sandstone, such as Penta- 
merus oblongus, Petraia bina, Cyelolites lenticularis, Strophomena depressa, Encri- 
nurus punctatus, §c. 
In addition to these are many nearly angular fragments of felspathic traps and 
ashes, and pieces of Silurian grits and slates. ‘I'hese beds, which are excellently shown 
along the shores of Dingle Harbour and the neighbourhood, are now called the Dingle 
beds. So far the continuous succession of conformable deposits is apparently unbroken, 
and may be tabulated as follows ;~ 
