^08 ME. D. C. EVANS ON THE OEDOVICIAN [1N"0V. I906, 



These beds are well exposed east of the ford at Ehydhenllan — up 

 the hill towards Llwynderw — near the mill — and on the road 

 immediately south of Henllan Church : they have yielded : — 



Dendrograptus sp. Orthis Car audi. Salt. 



Callograptus sp. Orthis Menapits (!) Hicks. 



Ogygia marginata, var. Siphonotreta sp. 



Ogygia Selwynii, Salt. Obolella sp. 



Trinucleus sp. Lingula sp. 



Ampyx sp. Orthoceras sp. 



JEglina sp. Theca sp. 



Beds of the same age occur at Blaenweneirch, and they have 

 yielded Ogygia marginata var. and Callograptus Salteri var. 

 attenuatus Elles (MS.). They are also seen in the dingle east of 

 Blaenweneirch, but have not yielded any fossils there. 



The grits of Cwmfelin-boeth pass up into gritty mudstones seen 

 on the road south of the entrance to Llangan Vicarage (Talvan). 

 These beds are very unfossiliferous, and have yielded only a few 

 fragments of dendroid graptolites too imperfect for identification. 

 However, there is no reason to doubt that they are what they 

 appear to be from their position. 



Mudstones of the same type occur near Penyglog, Cefnmeurig, 

 Llwyntreharn, and Pistyllgwyn, all of which have yielded 

 fragments of dendroid graptolites, and occupy a similar position in 

 relation to the grits. 



(5) Tetragraptus-Beds.— The lane leading up to Cilhenrhos 

 from Ehydhenllan, exposes a continuous section in shales and mud- 

 stones, showing the Ogygia-marginata Beds passing up to Tetra- 

 graptus-Shaies. Near Llebach a roadside-exposure in blue-black 

 shales has yielded Tetragraptus quadribrachiatus, Hall, T. Beadi, 

 Hall, Didymograptus extcnsus, Hall, JEglina (? ) binodosa, Salt., 

 Trinucleus sp., Theca, etc. 



Similar beds are seen near Henllan Farm, but here fossils are 

 generally scarce. About Penyback, on the western side of the dingle, 

 beds of the same age are frequently exposed, but fossils rarely 

 occur. 



Along the hill between Gellidiogyn lane and Cadwgan, shales are 

 continuously exposed, but fossils occur sparingly in them. Their 

 general character, however, is such as to render their identification 

 as Tetragraptus-B eds fairly certain. Beds of the same horizon are 

 also abundantly exposed on both sides of the dingle east of 

 Gellidiogyn. Fossils have been collected at several points between 

 Castell-draenog and Blaencediw, especially along the west side of 

 the ridge. The beds consist chiefly of blue-grey mudstones and 

 shales, and their fossil contents include : — 



Tetragraptus Headi, Hall. J JEglina sp. 



Tetragraptus Amii, Lapw. Trinucleus SedgwicJcii, Salt. 



Didymograptus patulus, Hall. Orthis calligramma, Dahn. 



Dichograptus sp. Lingulella sp. 



JEglina binodosa, Salt. 



