332 J. F. BLAKE AND W. H. HTTDLESTON OX 



The occurrence of a Lower Coral Rag, which is by no means con- 

 fined to this quarry, but underlies the oolites of the Lower Limestones 

 everywhere on the Hackness plateau, as may well be seen at the 

 Suffield limekiln, is a somewhat exceptional feature. Still there are 

 indications in several places throughout the Scarborough district of 

 something of the kind, though not on an equal scale. The horizon 

 of the Lower Coral Rag is situated towards the top of the gritty 

 limestones, which succeed the ball-beds of the Lower Calcareous 

 Grit. In the outcrops of the Lower Limestones this horizon may be 

 looked for wherever Spongia floriceps and brown rubbly masses occur 

 upon the surface. The chief features in the fauna are the great 

 variety of Ostrece, and the stunted character of the Mollusca &c. 

 generally. The spines of Cidaris are less than half the size of those 

 usually found in the true Rag ; we observe also curious micromorphs 

 of species which afterwards become characteristic of the Coral Rag, 

 such as Pecten articulatus, Astarterhomboidalis, &c. The peculiarities 

 above noted, together with the great abundance of Spongia floriceps 

 and Waldheimia Hudlestoni, may be deemed indicative of this group. 

 It is remarkable that at Scarborough and Filey, though nothing in 

 the way of corals beyond a few fragments of RhabdopJiyllia have 

 been discovered, these two fossils occur together on the corresponding 

 horizon. At the first-named locality we have noticed the Waldheimia, 

 though rarely, in the top shell-bed of B a (fig. 12) ; at the second 

 it is very plentiful along a line about 7 feet above the ball-beds. 

 This is a further corroboration of our view that the oolite of Scar- 

 borough Castle belongs to the Lower Limestones, whose representa- 

 tives at Filey must be sought for below the Filey-Brigg Calcareous 

 Grit. It will appear subsequently that there is a line of intermittent 

 coral growth, possibly more than one, towards the base of the Lower 

 Limestones, and also towards the base of the Upper Limestones in 

 the Pickering district. At Highworth, too, in the south of England, 

 we have a luxuriant coral growth surmounted by shell-beds belong- 

 ing to the Coralline oolite, whilst proof is given of the true Coral Rag 

 occurring at a higher level ; so that there is nothing unprecedented 

 in England in the phenomenon of a Lower Coral Rag. 



No. 7. The Basement-, or Passage-beds, which lie betwixt the 

 Lower Coral Rag and the Lower Calcareous Grit proper, are flaggy 

 ferruginous limestones, much quarried for road- and walling-stones. 

 Their thickness in some places is probably not much less than 24 feet. 

 Although portions of these beds are a mass of broken shells, the re- 

 cognizable forms are few, and consist of species common to most 

 parts of the Lower Calcareous Grit. Ostrea solitaria, Exogyra nana, 

 Gryphcea dilatata, Lima, sp. (small), Gervillia aviculoides, Pleuromya, 

 and Gresslya were noted. The irony character of these lower 

 passage-beds is well marked, but not so decided as in Scarborough 

 Castle Hill, Forge valley, and Beedale. It may be deemed a cha- 

 racteristic feature of the basement limestones of the Corallian series 

 in the Scarborough division of the Yorkshire basin. 



