616 ME. D. C. EVANS ON THE OED0V1CIAN [Nov. I906, 



hill vary a great deal in inclination, but are always northward, 

 bofch in the Didymograptus-bifidus and in the Arenig Beds exposed 

 here. Prom this fact it may be inferred that the overf old indicated 

 at St. Clear's is continued thus far west. The beds are also seen 

 at Middleway, and up the Llwynbrain Hill, where they are faulted 

 against beds of Lower Llandovery (?) age : fossils are, however, 

 rare, consisting of an occasional fragment, of graptolite or trilobite. 

 They are exposed abundantly in the lane leading up the hill from 

 Trevaughan. The ashes come out on this hill, and huge boulders 

 are profusely scattered about, ^sh-debris is traceable eastward 

 along the brow of the hill for some distance, but then ceases 

 abruptly, owing, presumably, to the beds being cut off by a fault, 

 or to their being overlapped by the Old Bed Sandstone. There is 

 certainly some faulting here, but the paucity of good sections renders 

 the structure difficult of interpretation. 



The only fossil- locality of any value hereabouts is on Gallt-y-beili 

 Farm, south of the Tave, and nearly opposite the railway-station. 

 This section has yielded : — 



Didymograptus bifidus, Hall. 



Didymograptus indentus, Hall. 



Diplograptus dentatus, Brongn. 



Mglina sp. Obolella (?) plumbea, Salt. 



Illcenus Hughesii, Hicks. | JBelleropkon ; etc. 



Trinucleus cf. Murchisoni, Salt. 

 Barrandea Homfrayi, Hicks. 

 Orthis sp. 



This outcrop runs westward into Messrs. Marr & Boberts's 

 ground, and possibly some distance up the valley of the Tave, but 

 there are no exposures here. 



In the neighbourhood of Llanfallteg, however, is another small 

 area occupied by these beds. A railway-section immediately north- 

 west of the Rhydywrach stream has yielded Didymograptus bifidus, 

 Hall, and Trinucleus cf. Etheridgii, Hicks. A small quarry in 

 mudstones, 100 yards or so north of Llanfallteg Station, has produced 

 a fairly-good series of fossils, including : — 



Didymograptus bifidus, Hall. 

 Didymograptus Niclwlsoni, Lapw. 

 Didymograptus a finis, Nick. 

 Didymograptus sp. 

 Diplograptus dentatus, Brongn. 



Climacograptus cf. confertus, Lapw. 



Glossograptus (?) . 



Pkacops llanvirnensis, Hicks. 



Barrandea Homfrayi, Hicks. 



Theca. 



Mudstones at Penybont, west of the Tave, have yielded Didymo- 

 graptus bifidus, Hall, and Ampyx cf. Salteri ; and at Bwlchmelyn 

 similar beds occur, where D. bifidus and an JEglina have been 

 collected. The beds here have been somewhat disturbed, especially 

 west of the well, but the dips are generally low. 



About a mile to the east is Bhydywrach, where there are several 

 exposures of shales and mudstones. That in the yard at Cefn- 

 maen-llwyd is particularly rich in fossils. The beds here are very 

 soft and of a light colour, the weathered portions being light fawn. 



