40 J: J. F. BLAKE AND W. H. HUDLESTON ON 



Plate XVI. 



Fig. 1. Fragment of unknown Crustacean, enlarged. Coral Rag, Upware. 



2. Avicula Icevis, Bl. & H., Hambleton Oolite, Kepwick, Yorkshire, 

 nat. size. 



3. Avicula Struck manni, De Lor., Trigonia-be&s, Osmington, nat. size. 



4. Avicula pteropernoides, Bl. & H., Lower Limestones, Thornton, 

 Yorkshire, nat. size. 



5. Modiola cancellata, Bom., Upper Calcareous Grit, Nunnington, 

 Yorkshire, nat. size. 



6. Avicula pteropernoides, Bl. & H., Trigonia-heds, Abbotsbury, nat. 

 size. 



7. Gryphaa subgibbosa, Bl. & H., Cement Stone, North Grimston, 

 Yorkshire, half nat. size. 



Plate XVII. 



Cone of Araucarites Hudlestoni, Carruthers, from the Coralline Oolite of 



Mai ton, Yorkshire. 

 Fig. 1. Basal portion of the cone, nat. size. 



2. Longitudinal section of the cone, nat. size. 



3. Detached scales, in part broken, showing seeds, nat. size. 



Discussion. 



Mr. Etheejdge spoke in high, terms of the merits of the paper, 

 with the opinions expressed in which he fully agreed. It required 

 immense experience and careful study to correlate the various beds, 

 which presented great palaaontological and petrological differences. 



Prof. Seeley said that he studied the Coral Rag in 1860-1866, 

 during which period he went all over the south-western and part of 

 the north-eastern region, in company with the late Prof. Sedgwick, 

 and had the advantage of discussing the various sections with that 

 distinguished geologist. He could not help being struck with the 

 heterodox character of the present paper, and contrasted the com- 

 plexity of its classification with the simplicity of Sedgwick's ideas of 

 the deposits referred to. He grouped the subordinate beds together 

 as unimportant divisions of the three grand series — the Lower Cal- 

 careous Grit, Coral Rag, and Upper Calcareous Grit. In the authors' 

 classification the term Coral Eag was restricted in its application, 

 and the Upper Calcareous Grit had disappeared from the southern 

 portion of the section. Sedgwick regarded the Weymouth section as 

 the most typical in all England ; and in going north these beds were 

 traceable as far as Oxford. In Central England, from Oxford to 

 Yorkshire, there was a series of clays most varied and instructive, 

 showing the reverse of much of the Coral-Rag area — namely, thin 

 limestones and thick clays. The Ampthill Clay, as this series had 

 been called, showed the fossils of the Coral Rag, but in a certain 

 way comprising Oxford and Kimmeridge Clay fossils. The French 

 geologists are in doubt as to what the Coral Rag is : in the Boulon- 

 nais the Kimmeridge Clay and Oxford Clay are greatly modified in 

 mineral character ; and no correlation by fossils is as yet possible. 

 Prof. Seeley stated that M. Rigaux is anxiously looking forward to the 

 publication of this paper in the hope that it will aid in correlating the 

 French series. He remarked that in England the subdivisions of the 



