LOWER LIAS FOSSILS. 43 
planorbis, but they are common enough in the clay-series, as in 
the Belemnite Beds of Golden Cap. Hooklets of Belemnites 
have been found by Dr. Hinde in the zone of A. angvlatus at 
Street ; while no other portions of Belemnite have at present been 
found at that locality. (See p. 81.) The term Belemnite Beds 
was applied in Gloucestershire by Prof. Tate to the zones of 
A. raricostatus, A. oxynotus, and A. obtusus ; although, according 
to his own lists, Belemnites are more abundant in the beds 
grouped by him in the zone of A. Jamesoni* and this appears to 
be the case generally. Dumortier has grouped the beds from the 
zone of A. Jamesoni to that of A. margaritatus inclusive, under the 
*' zone of Belemnites clavatus," thus including portions of our 
Lower and Middle Lias.f 
Small examples of Gryphcea arcuata (incurva) occur sparingly 
in the zone of A. planorbis, but the larger forms are most 
characteristic of the higher portions of the Blue Lias series, where 
they often occur in clusters at different horizons. At Fretherne 
in Gloucestershire particularly fine specimens are abundant. 
The form of this species is liable to variation, and in the higher 
beds of the Lower Lias, as at Cheltenham, we meet with the 
variety known as G. obliquata ; but G. cymbium also occurs. 
In a large series of specimens from one locality, many varieties 
may be noticed, and the intimate connexion of the several species 
may be admitted. These varieties were studied and illustrated 
by the late John Jones of Gloucester. J 
On coast-sections where we have an opportunity of studying 
the beds in section and in plan, as they are exposed in cliffs 
and in ledges or platforms on the foreshore, it is instructive to 
observe the distribution of the fossils. Such is the case on the 
Glamorganshire coast between Dunraven and Aberthaw, where the 
Lower Lias is continuously exposed for several miles in cliffs and 
in pavements. There we may notice how the organic remains 
occur in groups or colonies, abundant now and again at various 
levels. We can picture the evidence obtained in a quarry, where a 
Pentaci-inite-bed, a Gryphaa-beft, and a Zzwa-bed might be noted 
in succession ; but here on the foreshore we may observe groups of 
these fossils, sometimes in clusters, at other times intermingled, 
and at many different horizons, while the same bed appears quite 
unfossiliferous over the greater portion of its exposure. Such 
evidence warns us not to place too great reliance on the persis- 
tency of fossil-beds, and it explains why organic remains abundant 
at a certain locality at one time, have become rare later on, when 
the beds have been extensively worked. In this instance a 
number of fossil- beds are united in one or two zones (A. anyu- 
latus and A. Bucklandi). The evidence that may be obtained 
in places, suggests that fossils may sometimes be distributed in 
groups or clusters by currents that left no mark on the finer 
sediments. 
* Quart. Journ. Geol. Soc., vol. xxiii. p. 306 ; vol. xxvi. p. 398. 
f Etudes pal. Depots Jurassiques du Bassin du Rhone, Part III. p. 10. 
J Proc. Cotteswold Club, vol. iii., series of plates issued separately in 4to. 
