640 



MR. D. C. EVANS ON" THE OEDOVTCTAN [Nov. I906, 



The former contain crowds of Leptcena sericea, Sow.; and the latter 

 are almost entirely composed of Orthis, chiefly 0. testudinaria, 

 Dalm. 



These bands come out on the western side of Cwm-pal and in 

 the wooded ground near Dol-dderwydd. One band in particular, 

 composed of crowds of Orthis, is seen in the Old Pale lane, where it 

 reaches the top of the hill : this is probably the same as the 

 Cnycau Orthis-limestcme. The fossils collected from it are : — 



Orthis testudinaria, Dalm. 

 Orthis biforata, Schloth. 

 Orthis calligramma, Dalm. 



Orthis elegantula, Dalm. 

 Leptcena quinquecostata, M'Coy. 



Forest Tunnel has been excavated in beds of this age, and here 

 some of the limestone-bands are unweathered and full of fossils. 

 The dip here is almost vertical, and the beds are faulted against 

 Didymograptus-bifidus Beds on the north and against striped Lower 

 Llandovery (?) Flags on the south. The beds are traceable for about 

 200 yards westward, on both sides of the Tave, and then they 

 disappear entirely, being cut off by a fault. The fossils include : — 



Favosites fibrosa, Goldf. 



Pht/llopora Hisingeri, M'Coy. 



Petraia sp. 



Tentaculitcs avglicus, Salt. 



Calymene Blumenbachii, Brongn. 



Illcsnus sp. 



Trinucleus seticornis, Eaton. 



Trinucleus concentricus, Eaton. 

 Strojihomena rhomboidalis, Wilck. 



(very abundant). 

 Strophomena, corrugatella, Dav. 

 Lept&na sericea, Sow. 

 Orthis biforata, Schloth. 

 Orthis testudinaria, Dalm. ; etc. 



A slice of these beds has been faulted down among Didymograptus- 

 bifidus Beds at Forest : they are exposed at Forest Farmyard, and 

 at intervals between that place and a point south of Pant-y- 

 gwenyn. The fossils (which abound) are of the Tunnel type. 



(2) North of the Anticline. 



The black slaty DicranograptusShales are succeeded, north of 

 the anticline, by brown-grey mudstones, grits, and sandstones, in 

 all of which fossils are extremely rare — a few specimens of Orthis 

 being all that has been discovered in them. They possess no 

 character in common with the beds that succeed the Dicranograptus- 

 Beds on the south. They are somewhat like beds of the Redhill 

 stage, but much more like the Great Pale beds which will be dealt 

 with below. Their age must remain therefore an open question, till 

 further work has been done among them and more fossils discovered. 



(g) Lower Llandovery (?) Rocks. 



The last series (3) of beds pass up into conglomerates, grits, and 

 sandstones, with blue-grey mudstone partings. The conglomerates 

 are seen in situ at Pant-y-mwswm, and are here about 8 feet thick. 

 These are succeeded by grits and grey sandstones, well exposed 

 at Greystones. There are very few localities where these beds 

 can be seen in place, but their outcrop can be readily traced by 

 means of abundant loose blocks and debris. This strikes a more or 



