146 



DE. G. L. ELLES OX THE BALA COrXTET : [vol. Ixxviii, 



forms occnrring, and Ortliis (^Sarlcnessella) vespertilio being 

 especially abundant : — ■ 



Orthis (HarT^nessellaJ vespertilio 



(Sowerby). 

 Dcdmanella testudinaria (Dalman). 

 DalmaneUa elegantula (Dalman). 

 Strophomena fRafinesquinaJ expansa 



(Sowerby). 

 Plectamhonites sericea (Sowerby). 

 Asai^hi's poicisi Salter. 

 Calymene brevicapitata Portlock. 



Calymene planiinarginata Eeed. 



HomaJonotus sp. 



Triniideus of the concentricus type 

 (gihhifrons M'Coy r). 



Tri nucleus sp. nov. 



JEnci-inurus multisegmentah'S (Port- 

 lock). 



Monticulipora fibrosa (M"Coy). 



Glyptocrinus basalis M'Coy. 



The JFrondderw Asli then comes down to the stream, and sti'ikes 

 along it for about loO rards : it is here thinning out rapidly, and 

 seems to be really two thin ash-bands separated by mudstones. As 

 it leaves the bed of the stream to run up the opposite hillside a 

 second limestone lenticle is seen — this time, however, above the ash, 

 and with a quite different fauna from the other ; in this gasteropods 

 are especially abundant : — 



Lopliospira gyrogonia (M"Coy). 

 BeUerophon (Sinuites) bilobatus 



(Sowerby). 

 Murchisonia cf. simplex M'Coy. 

 Monticulipora fibrosa M'Coy. 

 Oi-thoceixis vagans Salter. 



Strophomena fRafinesquinaJ ex- 



pansa (Sowerby). 

 Ortiiis of tlie calligramma type. 

 Trinucleus of the concentricus type 



& sp. noT. 

 Glyptocrinus basalis M'Coy. 



This limestone lies at the base of the Allt-Ddu ^Mudstones. 



Y Garnedd. 



Thouc^h the beds at Y G-arnedd are much broken, vet the sue- 

 cession has features of especial interest, since some beds are better 

 developed there than anywhere else in the district, and it is the 

 locality where the Gelli-grin Limestone is definitely oolitic. Only 

 the higher Caradocian Beds are seen ; north of the main Llander- 

 fel road the Allt-Ddu ]Mudstones are well exposed, and exliibit the 

 usual bedding-surfaces denselv covered with fossils. The followinor 

 have been recoo-nized south-west of Pandv-isaf : — 



Orthis fHeterortJiisJ alternata 

 (Sowerby) & var. retrorsistria j 

 (Davidson). ■ 



Orthis (UalmanellaJ elegantula ; 

 (Dalman). 



Strophomena fRafinesquinaJ eipansa 

 (Sowerby). 



Plectamhonites sericea (Sowerby). 



Lingula ovata Sowerby. 

 Asaphus poicisi Salter. 

 Trinucleus sp. 



Glyptocrinus basalis M'Coy. 

 Beyrichia fTetradeUaJ complicata 



(M'Coy). 

 Orihograptus truncatus Lapworth & 



var. pauperatvs Lapworth. 



The higher beds of these Allt-Ddu Mudstones are seen on the 

 south side of the road, and with the Pont-y-Ceunant Ash and the 

 Gelli-grin Calcareous Ash are sharply folded, good exposures that 

 reveal the structui'e being visible on or close to the track running 

 between the Llanderfel and Lake-Yyrnwy roads ; there is an almost 

 continuous section of the Allt-Ddu Beds between the road and 



