and the Paleozoic System of England. 479 



The beds (in a quarry under Pen Cerrig House) which are 

 immediately under the recomposed trappean bed are made up 

 of an indurated Builth flag like that of the well-known Well 

 field quarries, and contain Ogygia Buchi and Diplograpsus pristis 

 in considerable abundance. 



The shales (No. 5) over the Pentamerus beds contain Grapto- 

 lites Ludensisy an unnamed Denbigh flag species of Atrypaj and 

 Orthoceras (?) ; and we found in them no other fossil. 



To exhibit the evidence in one point of view, I here subjoin a 

 list of fossils we collected from the beds in the above section, in- 

 cluding the flags of Wellfield quarries, which are a little further 

 south, but on the line of No. 3, and not far from its top. 



1st. From the Llanelwedd quarries of plutonic grit, &c. (the 

 building-stone of Builth), near the turnpike road. 

 Pyritonema fasciculus, the same as at Tre Cib near Llandeilo. 

 This species has sometimes been mistaken for an Ichthyo- 

 dorulite. 

 Orthis avellana. Leptcena sericea. 



O. calligramma, Pterinea. 



All of which are Cambrian species, i. e. are not found, so far as 

 we have seen, in any May Hill or Upper Silurian rocks. 



2nd. From a quarry east of Pen Cerrig. (No. 3 of the figure.) 

 Diplograpsus pristis. Ogygia Buchi (abundant). 



Ampyx nudus (very abundant) . Cytheropsis Aldensis. 



All the above are Cambrian ; and a much larger number of 

 Cambrian species from the same quarry is given in the pub- 

 lished list of the Cambridge Palaeozoic Fossils (p. 354). 



3rd. From a quarry west of Wellfield House. 

 Diplograpsus pristis. Ogygia Buchi (abundant). 



Ampyx nudus. Siphonotretra micula (in great 



Agnostus Maccoyi (Salter). abundance). 



All the above are exclusively Cambrian. In the Wellfield 

 grounds are some beds very much resembling the shales of 

 Shineton near Wenlock. Should the Olenus be found in them, 

 it will appear among its former associates and among rocks of 

 the same age with those of Hollybush and Shineton. 



4th. From the quarry below Pen Cerrig House. 



Petraia (as at May Hill; an unnamed species). 

 Ptylodictya lanceolata (Wenlock). 

 Pentamerus oblongus (in very great abundance). 

 Orthis pecten. 



No exclusively Cambrian species, and one exclu- 

 .sively Wenlock, hitherto, 

 r GrapioUtes Ludensis. 

 3. Upper shale, -s Atrypa (an unnamed Denbigh flag species). 

 <;.*,..., ^ f. {. Orthoceras {^) (Wenlock shale). 



2. Bands of Norbury 

 limestone, &c. 

 above the trap. 



