and the Palaozoic System of England. * 4^1 



through the conglomerates, which are finely exhibited between 

 Llandovery and Pumsant ; and at Bwlch Trebennau I found the 

 following fossils, which were determined by Mr. Salter : — 



Encrinite stems (abundant). Orthis elegantula (abundant), 



Favosites andother ill-preserved Atrypa crassa, 



corals. Calymene, small fragment not 



Turbinolopsis (a large species). specifically determinable. 



Lept(Ena sericea (abundant). 



The parcel containing this list never reached the Cambridge 

 Museum, and Bwlch Trebennau does not, therefore, appear in 

 M^Coy^s alphabetical list of "Lower Palaeozoic Localities*.'' But 

 I lately revisited the same spot, along with hirn ; and we pro- 

 cui*ed from it the two following species, Euomphalus tricinctus 

 and E. triporcatus. Both species are true Cambrian types ; and 

 the former helps us to connect the conglomerates of Trebennau 

 with those of Dol Fan. Taken collectively, the above list, how- 

 ever imperfect, seems clearly to indicate a group below the May 

 Hill sandstone, and is therefore Cambrian. 



.. IV. Intimately associated. with the above conglomerates, and, 

 I believe, on a lower geological stage, is a very great develop- 

 ment of rather earthy slates, and of arenaceous flagstones, some- 

 times coarse, and almost deserving the name of conglomerates, 

 in which case they are often ferruginous. The shaly slates of 

 this group are well seen in the high hills which form the water- 

 shed between Builth and Llandovery, both on the old road and 

 on the newer road by Llanwrtjd and the Sugarloaf. Beds 

 of the same general age range far up the hills on both sides of 

 the Towy above Llangadoc, and here and there show somewhat 

 rugged crests of hard, brown sandstone or conglomerate. 



This group is in some places extremely fossiliferous, and may 

 be well seen in an excursion northward from Llandeilo to Taliaris, 

 and round the hills near Garn Fawr. This excursion was made 

 by Mr. Salter and myself in 1846, and we obtained fossils from 

 the following localities, viz. below Taliaris, Park Lodge, Garn 

 Fawr, Cil-y-waun, and other places on our track. I have in my 

 note-book the lists made out by Mr. Salter, with which I will 

 not trouble the reader, as the fossils may be far better studied 

 in the Museum of Practical Geology than in the Cambridge col- 

 lection. But this I may state, on the authority of Professor 

 M'Coy, that so far as my lists and species go, they form a very 

 characteristic upper Bala group, and contain not so much as one 

 species which can be regarded as characteristic of a May Hill or 

 a Wenlock group. 



* At the same time was lost a small but valuable parcel, containing the 

 fossils from the neighbourhood of Devil's Bridge. 



