150 HIND : CARBONIFEROUS ROCKS OF ISLE OF MAN. 
have been formulated from time to time to explain the pecu- 
liar knoll-like character of the shelly limestones, Avhich I need 
not discuss here. As I mentioned above, corals are not common 
in the shell beds, but I have obtained specimens of Dibuno- 
phyllids, Lonsdaleia floriformis, Lithostrotion Portlocki, and other 
species, all of which indicate the Upper Dibunophyllum zone. 
Indeed, the Brachiopod fauna alone emphatically indicates this 
horizon to be of Upper Dibunophyllum age. 
It is probable, then, that the Poolvash shell-beds are of 
the same age as a part of the Castletown Limestones. They 
may be somewhat older, but they can scarcety be newer. They 
are certainly older than the upjDcr part of the Scarlet beds with 
Cyathaxonia. It will, therefore, be inadvisable to call the 
Castletown Limestones " lower " in future in relation to the 
Poolvash Series. 
The section given by Mr. Lamplugh on p. 54, op. supra cit., 
is interesting and important. 
The upper part consists of massive Pale Limestone, with 
bedding obscure and fossils abundant. Beneath are dark flaggy 
limestones with shaley partings, also fossiliferous, resting on 
a limestone breccia. 
The upper beds have the rich Brachiopod fauna mentioned 
above ; those below are full of corals, Dibunophyllids , Lithos- 
trotion cf. Portlocki, Clisiophyllum, Cyathophyllum cf. Mur- 
chisoni. Beds immediately below the section contain Productus 
giganteus, caninoid Campophylhtm, and other corals. 
The curious fact remains that both the Castletown Lime- 
stones at Scarlet, and the white shelly limestones at Poolvash 
are succeeded by the dark limestones of the Pendleside series 
i.e., the Posidonomya beds. 
The Limestones both of Castletown and of Poolvash, then, 
clearly belong to the Upper Dihunophyllum zone, the subzone 
of Cyathaxonia being also represented and being succeeded by 
black limestones and shales of the Pendleside series. 
It is only reasonable to infer, seeing the Scarlet, Balla- 
salla, Castletown, Langness, and Derbyhaven beds contain 
