594 MESSES. S. H. EEYXOLDS AND C. I. GAEDENEE [Nov. 1 896, 



The uppermost limestone is succeeded by calcareous nags and shales, 

 which are exposed in the Chair farmyard. Prom these we 

 obtained : — Agnostus trinodus, Salt., Agnostus, sp., Cyphoniscus soci- 

 alise Salt., Asaphus, sp., Trinucleus, sp., and Splicer exochus minis, 

 Beyrich. 



No other exposures occur till, at about | mile due east of the 

 Chair Farm, there is a small quarry showing hard micaceous grits 

 with shales above them dipping east at 24°. After this no more 

 exposures are seen. 



As we said before, owing to the compactness of the Chair lime- 

 stone and the absence of divisional planes, it is extremely difficult 

 to obtain any clear idea as to its dip and thickness. It is evidently 

 a lenticular mass, but appears to have been deposited in much the 

 same state as we now find it, and not to have assumed its lenticular 

 shape as a consequence of the folding and squeezing out of the 

 shales in the way suggested by Messrs. Nicholson and Marr x con- 

 cerning the Keisley Limestone. We never saw in it any signs of 

 crushing and folding, nor of the enclosure of wisps of shale, neither 

 are any of the fossils distorted. Nor did we see any evidence of its 

 being faulted against the rocks to the east in the manner suggested 

 by Messrs. Uarkness and Nicholson. 



The Chair limestone, as remarked by Messrs. Harkness and 

 Nicholson, is identical in many respects with the Keisley Limestone. 

 The two agree lithologically in varying as regards colour from red 

 to grey, and as regards texture from horny to crystalline. They 

 agree also most closely as regards their fauna. 



Although the Chair limestone can be divided into four fairly 

 well-marked bands, yet various forms range through it from top to 

 bottom, and it is probably all on much the same horizon. The four 

 most characteristic forms which range through it are : — Agnostus 

 trinodus. Salt., Illcenus Bowmani, Salt., Bemopleurides longicostatus, 

 Portl., and Cyphoniscus socialis, Salt. 



Though we obtained JStaurocephalus at a lower horizon, we care- 

 fully searched the upper beds without finding any forms character- 

 istic of the Staurocephalus-limestone which occurs immediately 

 above the Keisley Limestone in the Lake District. As, however, 

 nearly all the Proterozoic rocks south-east of the exposure of shaly 

 beds in the Chair farmyard are covered with drift, the Stauro- 

 cephalus-limesione may very possibly occur here, though it is not 

 now exposed. 



1 Quart. Journ. Geol. Soc. vol. xlvii. (1891) p. 508, and Marr, Geol. Mag. 

 1892, p. 101. 



