152 DE. G. L. ELLES 0>' THE BALA COr^'TET : [vol. Ixxviii, 



beds of the Ehiwlas Series mav be noted. The fossils from the 

 Calcareous Ash include the foUowins; : — 



Oi-this (Hai-knessella) vespertilio 



(Sowerby). 

 Orthis (PJectoHhisJ plicata 



(Sowerby). 

 Orthis fPlassiomysJ porcata 



(Sowerby). 



Leptsena rJiomhoidalis Wilckens. 

 Plectamhonifes sericea (Sowerby). 

 Plectamhonites riiombica (Davidson). 

 Plectamhonites transversalis (Dal- 



man). 

 Stropliomena deltoidea Conrad. 



Orthis (DalmanellaJ elegantula var. j Trinucleus concentricv.s Eaton. 



parva Eeed. > Trinucleus gihhifrons M'Coy. 

 Orthis (DalmanellaJ testudinaria Calijmene caractaci Salter. 



(Davidson). Pterygometopus juliesi (Salter). 



Orthis fs.s.J calligramma Davidson. Acaste ap)iculata (Salter). 



Orthis (Platystrophia) hiforata Lichas laxatus 'M'Coj. 



(ScUotlieini). Beyrichia complicata M'Coy. 



Orthis fXicol ell aj actonise {Sowevloj). , Monticulipora lycoperdon (Say). 



Triplecia (Cliftonia) spiriferoides \ Monticulipora fibrosa (M'Coy). 



(M'Coy). 



The fauna of the limestone appears to be much the same, 

 although, on the Axhole, individuals are not so numerous. 



Bryn-pig.-^ 



The chief interest of the Brvn-pig exposures is the occurrence 

 of the calcareous facies of both the Ehiwlas Beds and the Gelli- 

 grin Calcareous Ash Series in the same section, proving clearly (if 

 proof be needed) that on lithological grounds alone, apart from 

 any palseontological considerations, it is possible to discriminate 

 between the old so-called Bala Limestone and the Ehiwlas 

 Limestone. 



The main exposure is that forming a more or less sheer clif£-face 

 on the south-eastern flank of Bryn-pig, where the beds are seen 

 forming part of a syncline obliquely faulted through its centre. 



The lower of the two limestones is here especially well- 

 deyeloped; and is a beautiful, highly crystalline, dark blue-grey 

 rock, which on the north side of the hill is much veined with both 

 quartz and calcite, the presence of the quartz being due apparently 

 to the proximity of a fault along which there has been much 

 quartz mineralization. All along this north side of the hill the 

 lower rock has been extensively quarried for lime ; about 1 foot of 

 Calcareous Ash and 4 feet of pasty Ehiwlas Mudstone sejDarate it 

 from the lowest stratum of calcareous Ehiwlas Beds — that is, the 

 Ehiwlas Limestone. This limestone, as developed here, is neither 

 so crystalline in character nor so massive as in some of the more 

 westerly exposures (Creigiau Bychain). but is still definitely a lime- 

 stone ; towards the top the calcareous bands are separated by bands 

 of the pasty Ehiwlas Mudstone, which show up well on the 

 weathered surface by virtue of their cleavage : if we reckon all these 

 with the main limestone-band (about 6 feet thick), the calcareous 

 development of the Ehiwlas Series may be estimated as having 

 a thickness of 12 feet, and the occun-ence of abundant small phos- 



^ Probably Bryn-bedwog of the old Geological Survey lists. 



