150 



DE. a. L. ELLES OiST THE BALA COIJNTEY : [vol. Ixxvili, 



Orthis (PlectorthisJ ■ plicata 



(Sowerby). 

 Orthis (Plsesiomys) porcata 



(Sowerby). 

 Orthis (NicolellaJ actonise (Sowerby). 

 Orthis fDalmanella) elegantula var. 

 Orthis fDalmanella) test udinariay but. 

 Orthis nng^iis Sowerby. 

 Leptsena rhomhoidalis Wilckens. 

 Plectaynhonites sericea (Sowerby). 

 Plectamhonites rhomhica (Davidson). 



Lingula ovata Sowerby. 

 Pterygometopus jiikesi (Salter). 

 Cyhele sp. 



Trinucleus concentricus Eaton. 

 Beyrichia (Tetradella) coinplicata 



(M'Coy). 

 Monticulipora fibrosa (M'Coy). 

 Monticulipora lycoperdon (Say). 

 Monticulipora lens (M'Coy). 

 Cystid-plates. 



A good section of the upper beds is displa3^ed along an old cart- 

 track leading to the moor : this track runs at first across the strike, 

 and the Grelli-grin Calcareous Ash with the limestone above it is seen 

 dipping at 30° along the track. Just where the track bends round 

 so as to run at right angles to its former direction for a short dis- 

 tance, it runs parallel with the junction of the limestone and the 

 Rhiwlas Beds, which may be clearly seen on the south side resting 

 upon the limestone ; while higher beds are exposed still farther 

 along the track after it has resumed its original trend. These 

 Rhiwlas Mudstones contain : — 



Phillipsinella parabola Barrande. 



Lichas laxatus M'Coy. 



Encrinnrus sexcostatus Salter. 



Agnostus agnostiformis (M'Coy). 



Remoplenrides colhii Portlock. 



Remopleiirides sp. 



Stanrocephalus murchisoni Barrande. 



Illsenus davisi Salter. 



Trinucleus sp. 



Cheirurus himucronatus Mnrchison. 



Plumidites peachi (N. Etheridge). 



Orthis (Hehertella) crispa (M'Coy). 



PI ectamhonites quinqueeostata 

 (M'Coy). 



Stropheodonta corrugatella (David- 

 son). 



Christiania temiicincta (M'Coy). 



Slienidium sp. 



Very small Ostracods. 



Traced southwards the limestone is seen to bend sharpl}'' round 

 slightly above a little fir-copse, where the main road divides into 

 two, and this change in strike is Yevj obvious in a good exposure 

 close to the lower of the two roads. The Pont-y-Ceunant Ash also 

 exhibits this folding, but part of its outcrop is faulted off. 



The course of the limestone is marked hj dense vegetation, so 

 that wlien, as the result of the tear-faulting, the ash is brought 

 against the limestone there is little to distinguish the two in this 

 respect ; the feature due to the limestone dies away before Yspydd- 

 adog is reached, and not a trace of it is to be found in the streams 

 between Grelli-grin and the Moel-fryn quarries. 



Moel-fryn.^ 



The sections seen in the Moel-frj^n quarries are particularly 

 interesting : the ashy material, as a whole, is very much less con- 

 spicuous than at Grelli-grin ; no definite band of ash occurs at the 

 base, but there is a correspondingly greater thickness of cleaved 

 aslw mudstones and calcareous ashes, suggesting that the Pont-y- 



Probably Bryn-melyn of tbe old Geological Survey lists. 



