36 GASTEROPODA OF THE INFERIOR OOLITE. 



appear to make any show (I speak rather with hesitation on this point). There 

 can be no doubt, however, that in most places throughout the Dorset- Somerset 

 district, at all events from the sea coast as far as Castle Cary in south-east Somerset, 

 wherever the Upper Division of the Inferior Oolite is at all well developed, a shell- 

 bed rich in Gasteropoda is to be found about this horizon, and that in many cases 

 it contains Bhynch. spinosa. We shall see this further on, and we shall also see 

 that, in some places, there is a tendency to assume the lithological peculiarities of 

 the Ragstone. If we grant that Y 1 prefigures the Upper Trigonia Grit, we shall 

 have no difficulty in believing that the succeeding beds, including P 3 and P 3 , pre- 

 figure the Glypeus-grit, though not exactly corresponding as to details. Neverthe- 

 less, I consider that P 2 is somewhere about the horizon of the globata-bed, whilst 

 P 3 , in the abundance of its Myacids, reminds us of the name given by Lycett, viz. 

 Pholadomya-grit, to the uppermost beds of the Inferior Oolite in the Cotteswolds. 

 These two beds have not yielded me many species of Gasteropoda here — nothing, 

 in fact, of importance — but if they were well worked the case might be different. 



The section above detailed affords us the key to the remainder of the massif of 

 Inferior Oolite on its pedestal of Yeovil Sands in this vicinity. Still, there are 

 differences, and in one small quarry south of the village of Burton Bradstock, 

 where there is an exposure of about five feet, better traces of the Humphriesianus- 

 zone seem to exist . A recent road-cutting, leading from the village to the sea 

 coast, displays a complete section of the Inferior Oolite Limestone with the under- 

 lying impure Siliceous Limestones. Mr. H. B. Woodward, who was resurveying 

 this district in 1885, writes as follows : l " This excavation shows nearly the whole 

 of the Inferior Oolite (hereabout fifteen feet in thickness), and the junction of it 

 with the Sands beneath. . . . Many fossils were observed, although, owing to the 

 difficulty of extracting them, if not to the fear of injuring the banks, few were 

 collected. The entire Oolite is here a ' Cephalopoda-bed ;' but the so-called 

 Cephalopoda-bed of the Cotteswold Hills is no doubt represented by the upper 

 portion of the Sands beneath. The lowest portion of this Oolite represents in a 

 broad sense the zone of Ammonites Murchisonce (including the beds with A. con- 

 cavus) ; the highest portion represents the zone of Ammonites Parkin soni. The 

 zone of Ammonites Eumphriesianus, which is to be found in some quarries east of 

 Bridport, does not appear to be distinctly developed at Burton Bradstock, although 

 the species is met with in the cliffs and road-cutting." 



The above remarks will serve to afford an idea of those portions of the 

 country away from the cliff. But, since many of the specimens procured by the 

 most experienced collectors are obtained from old walls, or else from old disused 

 quarries, where the fossiliferous blocks lie about in the midst of grass-grown 

 sections, there wiD be a slight element of uncertainty as to the horizon of some of 

 1 ' Proc. Geo!. Assoc./ vol. ix, p. 203, 1886. 



