Vol. 67.] SALOPIAN ROCKS OF CATJTLET AND RAVE NSTONED ALE. 237 



The index to the map began with the Coniston Limestone Series. 

 The speaker had cut off the upper part of this under the name of 

 Fairy Gill Shale, which was the equivalent of that so well described 

 by Dr. Marr in the adjoining Lake District as Ashgillian. There 

 was a troublesome fossil at this horizon, the difficulty in respect of 

 which Davidson left unsolved. This was StropJiomena siluriana, 

 which had not yet been satisfactorily distinguished from the Orthis 

 hirnantensis of the upper or proper Hirnant Limestone, which the 

 speaker would regard as the equivalent of the very variable base 

 of the next division in the Authors' index — namely, the Stockdale 

 Shale, which forms the basement-bed of the Silurian. 



The Authors had attacked principally the enormous overlying 

 series of rocks, which, sometimes more sometimes less sandy, but 

 rarely justifying the name of grit, appeared to be the Northern Type 

 corresponding to the Wenlock and Ludlow of South Wales. They 

 had not here, as in the case of the Southern Type, well-marked 

 limestones (the Woolhope, the Wenlock, and the Aymestry Lime- 

 stones) to help them to run lines across an obscure country ; but, by 

 working out the graptolithic fauna of every available exposure, 

 they had succeeded in correlating the sequence with that of other 

 better-known areas, especially with that of Scandinavia. Such a 

 work required great knowledge, care, and staying power, qualities 

 by which the Authors had made a notable advance in geological 

 research. 



Dr. Marr, replying, in the absence of the Authors, remarked that 

 there was nothing to answer, but that he wished, as one who knew 

 the district, to express his satisfaction with the detailed and 

 accurate results obtained in an area where, owing to the some- 

 what monotonous uniformity of lithologieal characters, separation 

 of the zones by such characters was almost impossible until the 

 fossil horizons had been determined in the manner pursued by the 

 Authors. 



