Illsenus Eowmanni, Salt. 

 Stygina latifrons, Portl. 

 Trinucleus seticornis, His. 



488 J. E. :maePv k^J) t. eobeets ox the 



creat. Tvrone, judging from an examination of the specimens pre- 

 served in the Museum of Practical Geology. Amongst the fossils 

 common to Sholeshook and Desertcreat are : — 



Pliacops Brongniarti, Portl. 

 Stauroceplialus globiceps, Portl. 

 Eemopleurides dorso-spinifer, Portl 



The absence of cvstideans at Desertcreat is noticeable. 



A large number "^of fossils are recorded from this Irish locality, 

 which seem to show that the representatives of the Eedhill stage 

 occur there also. 



In Sweden the same fauna appears at the same horizon in beds 

 of precisely similar lithological character. Immediately above the 

 beds correlated with the Middle Bala series, in Westrogothia, Dr. 

 Linnarsson's Staurocej^halus-'beds (at the base of the Brachiopod- 

 schists) contain Staiirocej)7ialus clavifrom, Ang., Proetus hrevifrons, 

 PJiacojys mucronatiis, Calymene tuberculata, Acidaspis centrina, 

 Trinucleus WaJilenhergi, Agnostm trinodus, PMllipsia parabola, 

 and Panderia megalopMudma (Linnarsson, ' Om Yestergotlands 

 Cambriska och Siluriska Aflagringar,' p. 51). 



In Scania also the same bed occurs. Dr. Tullberg (' Skanes Grap- 

 toliter,' i. p. 17) records in his zone ^ith. Stauroceplialus clavifrons : — 



Stauroeephalus clavifrons, A7ig. 

 Phacops inucronata, Ang. 

 Trinucleus Wahlenbergi, Eouaidt. 

 lUaenus, cf. Salteri, Barr. 

 Proetus brevifrons, Ang. 

 Cheirurus. sp. 



Ampyx tetragonus, Ang. 

 Phillipsia parabola, Barr. 

 Acidaspis, sp. 

 Calymene Blumenbacbii, 

 Agnostus trinodus, Salt. 

 Dentaliiim, sp. 

 Turbo, sp. 



From the general occurrence in this zone of Stauroeephalus globi- 

 ceps, or a closely aUied species, it may be conveniently spoken of as 

 the Stau rocepha lus-zone. 



(b) Pedhill Stage. — This stage is lithologically like the Ashgill 

 shales of the Lake-district, which also immediately overlie the 

 StaurocepJicdus-zone. In Scotland the " soft blue mudstones, 

 homogeneous, thick-bedded, and more or less concretionary in 

 structure," described by Prof. Lapworth as occurring above the 

 Starfish-bed of Lady Burn, in the Girvan area, seem to be likewise 

 similar (Q. J. G. S. xxxviii. p. 619). 



In Scandinavia the beds with Phacops eucentra, Ang. (a variet}- 

 of P. mucronatus ?) , which immediately succeed the Stauroceplicdus- 

 zone in Scania and Westrogothia, have elsewhere (Q. J. G. S. xxxviii. 

 p. 321) been compared by one of us with the Ashgill Shales of 

 Britain. 



(g) Slade Beds. — These are not precisely like any beds known to 

 us as occurring about the same horizon in other areas. 



In the Lake-district a mottled grey limestone with many 

 brachiopods occurs immediately above the Ashgill Shales and below 

 the Birkhill beds in Skelgill Beck. Like the Slade beds, it is 

 marked by the occurrence of Climacograptus and the absence of 

 Monograptu^. 



