48 THE CARBONIFEROUS LIMESTONE OF SOUTH-WEST GOWER 
section occurs, yielding vast numbers of organic remains, 
very varied in character. The most interesting feature 
presented is five distinct Gastropod layers, the highest of 
which may be taken as the top of sub-zone Of the 
Gastropods I can only as yet refer to genera ; several of 
them are, I believe, new species, and some possibly peculiar 
to the district. In the highest of these gastropod beds 
(I), which is two feet in thickness, are found Belter ophon sp., 
Loxonema sp., Dentalium {priscum ?), and Platyschisma sp. 
Forty-eight feet of limestone (tl),^ yielding Lithostrotion 
affine and a few specimens of Belter option, separate Gastro- 
pod Beds (I) and (II), which latter (II), 5 feet in thickness, 
contains the same species as (I), but in greater numbers, 
Dentalium being especially common. Bed (III) lies 2 feet 
below this and is a thin layer, with apparently no other 
species than those found in the two higher beds. Below 
this third bed are 15 feet of limestone (12), in which a few 
scattered examples of Bellerophon sp. Lithostrotion * affine 
and Syringopora are the only fossils. Bed IV, the 
thickest of the series, measuring 25 feet, yields in 
abundance Loxonema, Platyschisma, Euomphalus, Murchi- 
sonia, Pleurotomaria, Natica ? Naticopsis, Bellerophon, and 
Dentalium, with Orthoceras laterale, Orthoceras Nautilus, 
and Modiola ? In the last 12 feet of this interesting layer 
the shells are nearly all in fragments, with a few perfect 
specimens of Platyschisma and Loxonema. 
The succeeding bed, 6 feet in thickness, contains merely 
the persistent Lithrostrotion affine, and rests on a base 5 feet 
thick, crowded with broken crinoid stems, few traces of 
which occur in any of the previous layers. Beneath this 
we have about 90 feet of alternating limestones and bright 
red shales (13), the latter usually only a few inches thick, 
and showing on their surfaces a matted mass of Lithostro- 
tion affine, L. Martini, Syringopora sp., and crinoid stems, 
1 Vide Section B, on page 45. 
