Yol. 56.] SILURIAN SEQUENCE OE EIIAYADEE. 121 



About j mile east of Ehayader, in the banks of Ehyd-hir Brook, 

 a section of a somewhat higher set of shales is visible. The rock 

 is intensely cleaved : with patient industry, however, fragments 

 of a few graptolites of the following species may be collected : — 

 Monograptus SedgwicJcii var. distans (?), M. intermedins, Carr. 

 31. crassus, and Climacograptus ecctremus. These forms appear to 

 belong to the same horizon as that of the Tannery and the Glan 

 Elan beds. Farther east several new species appear. One very 

 fair exposure occurs in the Ehyd-hir east of Beili-newadd. The 

 lower beds are of the ordinary pale shale-and-mudstone type ; but 

 higher up the group, in the plantations east of the farm, a set of 

 false-bedded, impure, micaceous grits make their appearance. These 

 are banded with thin carbonaceous seams yielding poorly-preserved 

 examples of Monograptus priodon, Bronn. If a collection of 

 graptolites, however, is desired, one cannot do better than visit the 

 small stream west of Llwyn-y-Baedd. In the brook west of the 

 quarry, many of the exposed shales are crammed with well-pre- 

 served examples of Monograptus priodon and M. exiguus, Nich. 



At Cwm Barn, about J- mile farther east, the base of the Ehayader 

 Series is made up of intermingled grits and shales. The appearance 

 of this new set of conditions is perhaps rather startling at first 

 sight ; and I was at one time inclined to believe that the Gafallt 

 Group had once more appeared between the Ehayader and Gwas- 

 taden Groups. But the included fossils prove conclusively that 

 these arenaceous rocks are merely a local development of the 

 Ehayader beds which we have been studying. The lower division 

 consists of alternating pale grey calcareous shales and impure 

 grits, with occasional thin seams of limestone. The shales weather 

 to a characteristic dark brown. Opposite the old quarry, and in 

 the old quarry itself, thin beds of soft rotten conglomerate are 

 exhibited. These are highly fossiliferous, and yield the forms 

 enumerated in the following list : — 



Atrypa reticularis, Linn. 



imbricata, Sow. 



Leptcena rhomboidalis. 



sericea (!) Sow. 



transver salts. 



Meristella sp. 



Orthis ccdligramma, Dalm. 



Orthis elegantula. 

 Pentamerus sp. 

 Spirifer sp. 



Stropkomena pecten (!). 

 Favosites gothlandica, Fougt. 



(Stenopora) fibrosa, Goldf. 



Petraia bina, Lonsd. 



In addition to the foregoing I have detected Monograptus Sedg- 

 wicJcii var. The dip is about 28° north-westward. 



Above the quarry the grits become rather thicker, attaining a 

 thickness of 3 or 4 inches. They are black-banded, as a rule, yielding 

 Monograptus priodon and M. SedgwicJcii var. The total thickness 

 of this grit-series up to the first hedge is about 150 feet. Beyond 

 this point the grits commence to thin out, and pass up into pale 

 blue-and-grey shales, barren of fossils. About 500 yards above 

 Cwm Barn the rocks are obscured by Drift, and no further sections 

 are revealed. 



