HIND : CARBONIFEROUS ROCKS OF ISLE OF MAN. 149 
environment. The Brachiopoda are generally perfectly pre- 
served, and the valves are in contact, and those with spiral 
internal arrangements have them preserved. I have come 
to the conclusion that these facts indicate an original shell 
bank, which was subsequently covered up by the shales and 
dark limestones of the Pendleside series. 
This condition of things at Poolvash is by no means unique. 
Similar knoll-like shell beds occur at Park Hill, Thorpe Cloud, 
Xarrowdale, Wetton, Castleton, Clitheroe, Withgill, and the 
Cracoe Fells, in all of which is found identically the same fauna 
that characterises the Poolvash Limestone. The general char- 
acters of these shell beds are very similar. They are composed 
of White Limestone, from which the shells are easily cracked 
out. All sorts of MoUusca, Bracliiopoda, and fish teeth are 
jumbled up together, rendering the bedding planes very in- 
distinct. These shell beds appear to occur at, or nearly at, 
the top of the Limestone Series, and to lie in all cases imme- 
diately below the Posidonomya Becheri beds. 
The relation of these shell beds to the Cyathaxonia beds 
is obscure, and generally where the one is present the other 
seems to be absent in the passage from the limestone series 
to the shales, though owing to the very local character of the 
shell beds, these two terms in the Upper DihtinopJujUum zone 
may be not very far apart. For example, at Elbolton, Hill 
Stebden, and Keal Hill, of the Cracoe Fells, the shell beds are 
apparenth^ succeeded by shales of the Pendleside series. At 
Butterhaw and Hill Skelterton there is a passage up from 
well-bedded limestones with many stools of Lithostrotion and 
other corals through Cyathaxonia beds to the Posidonomya 
Becheri beds. 
The shell beds are characterised by the presence of Reti- 
cularia lineata, Martinia glabra, Spirifer ovalis, S. planicosta, 
Sckizophoria resupinata, and many other Brachiopods typical of 
a high fauna. They are also all characterised by abundance 
of Glyphioceras crenistria, G. truncatum, and G. ohtusum, 
amongst other Cephalopods. At any rate, then, the Poolvash 
Limestone and fauna are well known, and have been studied 
in many localities on the Mainland. Various elaborate theories 
