BRITISH SILURIAN BRACHIOPODA. 137 



Genus — Cyrtia, Balman, 1827. 



19. Cyrtia exporrecta, Wald. Dav., Sil. Mon., PI. IX, figs. 13—24 ; Sil. Sup., PI. 



VI, figs. 13, 13«; and PI. VIII, figs. 4, 5. 



At p. 102 of Qiy ' Silurian Monograph, I say,' " In England Sp. exporrecta ranges 

 from the Lower Llandovery to the Ludlow. Since then Dr. C. Callaway has found an 

 unmistakable specimen of this species in the Horderley sandstone at Chatwall, Salop, 

 and of this I give a figure (Sup., PI. VIII, figs. 5, 5(2), He writes me that the horizon is 

 about the middle of the Caradoc series. The subdivisions of the Salopian Caradoc in 

 the descending order are : 5, Trinucleus shale ; 4, Onny flags ; 3, Horderley sandstone 

 (horizon of the C . exporrecta) ; 2, Hamage shales; and 1, Hoar-Edge grits. This is the 

 first and only specimen of the species I have seen or heard of so low down as the Middle 

 Caradoc. Cyrtia exporrecta was found by Mrs. R. Gray on the Upper Llandovery at 

 Penkill in the Girvan district. 



The Rev. Norman Glass has developed the spirals of this species as well as their 

 attachments and, of these figures will be found in PI. VI of this Supplement. 



Genus — Spirifera, Sowerby {Spirifer), 1820. 



20. Spirifera pijcatella, Linne. Dav., Sil. Mon., PL IX, figs. 1 — 8 ; Sup., PI. VI, 



figs. 11, 12 ; and PI. VIII, figs. 2, 3. 



The exact stratigraphical range of this variable species has not yet been completely 

 determined. We know positively of its presence in the Llandovery, Wenlock, and Ludlow 

 formations. In the Explanation of Sheet 15 of Map of the Geol. Survey of Scotland, 

 p. 15, 1871, Mr. R. Etheridge quotes it from the Caradoc of the Leadhills district in 

 Scotland. The specimen upon which this identification was founded has been lost or 

 mislaid, as it could not be found among the specimens from that locality in the Museum 

 of the Geological Survey of Scotland. I believe the identification to be a mistaken one, 

 as all the other Brachiopoda I have been able to examine from that locality were Caradoc 

 species, with no trace of Sp. plicatella among them. 



In Scotland, Sp. plicatella, var. radiata, was found plentifully by Mrs. R. Gray in the 

 Penkill beds (Upper Llandovery) at Bargany Pond Burn, Girvan, also at Penwhapple 

 Glen in beds of the same geological age. 



The variety _^/o(5o5«, Salter (Dav., Sil. Mon., PI. IX, figs. 7, 8), seems to occur under 

 the name of Spirifer Davoiisti de Verneuil, in the Lower Devonian at Brulon, Sarthe, 



