(^Ty-draw Slates). 



198 DE. ^^'ILLS AXD ME. SillTH OX THE LQWEE ^vol. lixviii, 



the Xant-Ty'n-v-tv\Tiipath stream, in the neiglibourhood of the 

 Glvn-Ceiriog-Glvn-DTfi'chvT road. 



The following appeal's to be the sequence in this area : — 



SECTIO^"■ TP THi: Xaxt Tt'>*-t-twxpath. 



Tfiicliness in feet. 



-^x- 1 1 r Banded earthy-weathering slates. Cyr- 



[ tograptus-rnurcnisoni Zone, 



( (5) Bine slates, interbedded in the lower 



I part with grev mndstone of the 



Tarannonor [ Tarannon type. Monograptus- 



irpperValentian-{ crenidat us Zone 10 



(4) Grey-green mndstone, with ocea sional 

 striped bands, cleaved into thick 



1^ roofing-sJates abont 140 



f (3) Pale gritty shale, with brachiopods. 6 



[ (2) Speckled or mottled, rather gritty 



Lower Talentian j green slates 70 



(Fron Frys Slates). | (1^ Platy sandstone with shale-bands, 

 j passing down into more thickly- 



[ bedded sandstone 2 



Ashgillian. Glyn Grit. 



In the Lower Talentian no graptolites have been found, but in 

 places brachiopods are fairly numerous. Although for the gi-eater 

 part these are Lower LlandoTerr forms, yet some, in Prof. 0. T. 

 Jones's opinion, are more typical of the TTpper Llandovery. The 

 folio wins: forms were identilied by him. Fossils collected from a 

 point 120 yards south-east of Cefn-isaf, near Grlyn-Ceiriog, were : — 



Camarofcecliia horealis Schlotheim. Orthis cf. rii-stica J. de C. Sowerby. 



Catazyga ('?). Orihis {DalmaneUa) sp. 



Leptsena r7joni6oif?aZi5 "Wilckens. cf. OHJiotete-s pecteyi Linnasns. 



Leptsena sp. nor. Penfamerusglohosus J. deCSoweihj. 



Meristina fnrcata J. de C. SoMreThj. Plectamhonites dxiplicata J. de C. 

 Meristina suhundata M'Coy. Sowerby. 



Meristina sp. Plectamhonites scissa Salter. 



Orthis (Bilobites) hiloha Lirmiens. PI ecto mbonites cf. transverscdis 

 Orthis {HeberteUa) protensa J. de C. WahL 



Sowerby. . Acidaspis sp. 



In an old quany on the right bank of the Xant-Ty"n-y-twmpath 

 the following were discovered : — 



Catazyga (?J. i Plectambonites scissa Salter. 



Meristina cf. subimdata M'Coy. Plectamhonites cf. transrersalis 



Orthis {Dalmanella) sp. | "W'ahL 



The brachiopods enumerated above occur in the uppermost part 

 of the Lower Talentian . 



In the Upper Talentian a few graptolites have been discovered. 



The crenidat lis beds are recognizable here, as elsewhere, by 

 their dark-blue colour, at the summit of the Tarannon pale slates. 

 The following fossils were foimd at Xant-Fowc, a mile and a half 

 south-east of Glyn-Ceiriog : — JIo nog rapt us ro»?6'm??/.s Nicholson, 

 and Jl. vornerinus var. crenidatus Tomquist. 



The presence of the griestonensis zone is suggested by the 



