On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 541 
limestone, are three beds which are easily distinguished by their remarkably 
parallel and symmetrical arrangement. These are the fish-beds of the limestone, 
as distinguished from those already mentioned in the Lower Shales. It is from 
these beds that the magnificent: spines of Ctenacanthus major, Ag., have been 
obtained ; the great teeth of Psammodus and numerous others have also been found 
here. _ Beyond the fish-beds a number of interesting beds occur, a series, about 167 
feet in thickness, are Oolitic in structure. The limestone in the Great Quarry is a 
lighter gray in colour; between the beds there is frequently a deposit of crystals 
of fluor spar. 
Above the thick limestone there are about 400 feet of upper limestone shales 
which pass gradually into the millstone grits, 1,000 feet in thickness. 
The following section exhibits the series of strata between Cook’s Folly and the 
Black Rock Quarry :— 
NW. Cook’s Folly. Black Rock Quarry. S.E, 
NOEN 
s) oY Qo is | 
5 Ep @ ps E 
63, Ze 8 i= t=P 
S ae. s m eel 
B 5 S 5 S 
3 iS SL Bo 2 
Sot =] 
5 z go 
.- ~~ é 
Fic. 3, Section in THE Avon VALLEY, NEAR BRISTOL. 
a, Mountain Limestone. b. Lower Limestone Shales. c. Old Red Sandstone, on! 
The Farlow and Oreton Limestone forms an outlier of small extent at Titterstone, 
Clee Hill, in Shropshire. The hill rises from a depression of the Old Red Sand- 
stone near Cleobury, and its flanks exhibit the whole of the Carboniferous series 
as developed in that district. Above the Old Red Sandstone are the Carboniferous 
Shales and Limestone, surmounted by the Millstone Grits and Coal Measures, which 
are capped by a considerable mass of basalt which has been’ forced by voleanic 
action through the entire series and overflowed the top of the hill. The following 
sketch from Murchison’s “ Siluria ” very clearly exhibits the series :— 
Fic. 4, Secrion across Lirrersrone, Cues Hint, SHropsuire (ArTER Murcuison). 
a. Old Red Sandstone. d. Coal-measures, 
| 6. Carboniferous Shale and Limestone. e. Erupted basalt. 
ec. Millstone Grit. 
