92 Re-ports & Proceedings — Geological Society of London. 



The Wenlock Shales below the limestone are divisible into an 

 upper portion, which consists of sandy shales and sandstones, and 

 a lower portion composed of mudstones. The Coed-y-paen Anticline 

 has been much affected by pressure, the hard Wenlock Limestone 

 Bed has been fractured in no fewer than twelve places, and portions 

 of it driven in on to the soft underlying shales. 



In the northern part of the area there is much alluvium and drift ; 

 consequently, although no Wenlock Limestone is now to be seen 

 beyond the Wenlock Shales, it is possible that the limestone may 

 occur beneath the drift, as, when last exposed, the Wenlock Shales 

 az*e seen dipping north-eastwards, and beyond the drift Ludlow Beds 

 are observed near Clytha. The Llangibby Anticline extends as far 

 north as Cwm Dowlais, and shows Ludlow Beds resting upon 

 Wenlock Limestone, the anticline ending against an east-and-west 

 fault. North of Cwm Dowlais nothing but Ludlow Beds are seen 

 between the Coed-y-paen Anticline and the Old Red Sandstone, from 

 both of which they are faulted. 



An account of the Ludlow Beds along the western and eastern sides 

 of the inlier is given, and a large amount of evidence with regard to 

 the ages of the rocks at numerous exposures is produced in the form 

 of lists of fossils. The fossils have all been named by Dr. F. R. Cowper 

 Reed, who contributes an appendix in which several new species and 

 varieties are described in detail. 



2. " Some observations on Cone-in-Cone Structure and their relation 

 to the Origin." By Samuel Rennie Haselhurst, M.Sc, F.G S. 



In a brief review our state of knowledge is summarized, and the 

 deductions of other investigators are analysed. 



The author then outlines the phenomenon of megascopic pseudo- 

 stromatism, and certain tectonic features which are always associated 

 with cone-in-cone structure in areas where it is greatly developed. 

 He points to the disadvantage accruing from many observers not 

 having seen it in situ on a large scale, and shows how a simulation of 

 horizontality in stratification marks what he takes to be the key to 

 the diagnosis of this structure. 



Two typical areas are described : — 



(1) The St. Mary's Island - Tynemouth district of the D 5 Coal-measures of 



Northumberland. 



(2) The Hawsker - Eobin Hood's Bay - Eavenscar district of the North 



Biding of Yorkshire. 



The specimens collected in these areas are unique, and some dozen 

 types from other areas, including Sandown, Portmadoc, Olney, 

 Somerton, Lyme Regis, and Merivale Park, are examined in detail 

 with reference to — 



(1) Evidence furnished by distorted fossils. 



(2) Cbemical composition. 



(3) Geometrical similarities. 



(4) Microscopic structures. 



The author critically examines the accepted hypothesis that 

 cone-in-cone structure is something essentially due to crystallization. 



