180 



DE. WILLS AND ME. SMITH ON THE LOWEE [vol. IxxVlii, 



Table I. 



The Bala Formation. 



Glyn-Ceiriog 

 District. 



Moel-Fferna 

 District. 



Cyrn-y-Brain and 

 Myny dd- Cricor . 



8. GlynGrvit. CorwenGrrit. Plas-uchaf Gr it . 



(6) Massive, fine-grained, Massive, fine-grained. Massive ashy grit, and 

 uncleaved grit. uncleaved grit. on Cricor platy grits 



and shales. 



(a) Thinly-bedded fossili- 

 ferous grit or sand- 

 stone, locally inter- 

 bedded with platy 

 limestones. 



7. DolhirBeds. 



(6) Ver}^ fossiliferous, 



cleaved, micaceous 

 shales, with some cal- 

 careous bands. 



Chasmops macroura, 

 Sarpes dorani,Sjphce- 

 rocoryphe thomsoni, 

 Phacops hrongniarti, 

 Trinucleus seticor- 



7. Dolhir Lime- 



stone. 



(a) Limestone containing 

 corals, interbedded 

 with shales. 



Absent, ? by faulting. 



Dolhir Beds. 



(6) Cleaved shales, 

 usually less fossili- 

 ferous and more 

 sandy than at Glyn. 



As near Gljai, but with 

 Meristina crassa 

 near the top. 



T y ' n - V - 1 w m p a t h 

 JBeds. 



(a) Compact, grej--, 

 cleaved shale, some- 

 times speckled. Few 

 fossils, except locally. 



Agnostus agnosti- 



formis, Trinucleus 

 seticornis, Phillip- 

 sinella parabola, 

 Phacops truncato- 

 caudatus. 



Blaen-y-cwm 



Beds. 



Dark-blue or black 

 graptolitic mud- 



stones, poorlj^ cleaved. 



? Zone of Diplograp' 

 tus pristis. 



Cyrn-y-Brain 

 Beds.i 



[b) Tough, ashy, cleav- 

 ed grey \vf. eke shales 

 and sandstones, and 

 one thin fossiliferous 

 ash-band, on soft, 

 micaceous, very fos- 

 siliferous sandstone. 



Calymene senaria, 

 Phacops brongniarti, 

 Chasmops macroura, 

 Meristina crassa, 

 Orthis hirnantensis, 

 Clitambonites ascen- 

 dens. 



1 Not to be confused with the Gwern-3'-brain Group in the Welshpool district, 

 described by Dr. A. Wade, Q. J. G. S. vol. Ixvii (1911) p. 422. 



