DORSET-SOMERSET DISTRICT. 45 



that lie saw in some collections fossils from his own fossil-bed at Bradford Abbas 

 marked " Lias." Now, if we regard the " Marnes Infra-oolithiques " of Eugene 

 Deslongchamps as forming a portion of the Lias, then the concavus- or Soiverbyi- 

 bed of Bradford Abbas will fall into that category ; but in this case the greater part 

 of the Inferior Oolite in England will have to be relegated to the Lias, a proposition 

 which must not be entertained for a moment. At the same time it cannot be too 

 often insisted on that our Soioerbyi-bed forms no portion of the Oolite of Bayeux. 

 It distinctly belongs to the Lower Division of the Inferior Oolite, and constitutes its 

 highest member. Hence we shall find that the Gasteropoda differ considerably 

 from those of the Bayeux Oolite, and that is one reason why so many species 

 hitherto unknown are found there. It follows from this that Dr. Wright was 

 equally mistaken when, rushing from one extreme to the other, he afterwards 

 placed the Bradford Abbas fossil-bed in the Hamphriesianus-zone (' Quart. Journ. 

 Geol. Soc.,' vol xv). 



Amongst the Gasteropoda of the "fossil-bed" there are several species of 

 Purpurina, some decidedly new. Spinigera is well represented, and that too by 

 some new and curious forms. The species of Alaria are not without resemblance 

 to those described by Schlumberger from the East of France. As regards 

 Cerithium, the prevailing species in the beds of Bayeux are here represented by 

 related rather than by identical forms, whilst the rarer and less widely distributed 

 species would appear to be altogether different. Much the same may be said with 

 regard to the other genera, and if we seek for a complete antithesis in England, it 

 may be sought in the almost equally rich shell-bed (PJ at Burton Bradstock, 

 which contains extremely few species identical with those of the bed now under 

 consideration. The exact equivalents of the "Sowerbyi-hed," as known in North 

 Dorset, are by no means clear in the Cotteswolds, nor, for the matter of that, in 

 any other part of England, so far as I am at present aware. 



The two thin beds which succeed in the quarry are of but little interest for us. 

 The " rotten-bed," which is so full of Astarte obliqua, may possibly be an attenuated 

 representative of the Humphriesianus-zcme. In point of thickness more than half 

 the quarry belongs to the Parkinsoni-zone. Here we would fain institute a 

 comparison with the same zone as developed at Burton Bradstock. The condi- 

 tions are different, however, and we can hardly see in the marl-bed with T. Morleri 

 the exact equivalents of F v Nevertheless, both here and in the white limestone 

 above, the species of Gasteropoda which do occur are mostly identical with those 

 noted from the same horizon on the coast. 



Halfway-House Quarry is rather nearer to Bradford Abbas than to Sherborne, 

 and to some extent partakes of its nature and characteristics. I do not know of 

 many Gasteropoda having been obtained from here. The usual grey calciferous 

 grit called the " Dew-bed " forms the base, and above this occur some four feet of 



