184 THE GEOLOGICAL AGE OF CENTRAL AKD WEST CORN-WALL. 



6. 0. Berthoisi {Ronald) var. Cornuliensis {Dav.)= 0. turgida 

 (McCoy). This occurs both, at Caerhayes and 

 Manaccan — as well as in the Budleigh-Salterton beds 

 and the "May" beds in Brittany. At Budleigh- 

 Salterton it occurs in a ferruginous rock, but never with 

 Strophomena grandis or its associates (v. remark on 

 S. grandis swpra), figured by Davidson loc. cit. Speci- 

 mens may be seen in the Truro Museum. 0. turgida 

 {= 0. Berthoisi) is given by Murchison as Llandeilo and 

 Caradoc. Salter has described this same fossil from 

 Budleigh-Salterton under the names of 0. striatula 

 {JEmm.), and 0. redux {Barr.), and supposes them to be 

 Llandeilo. 



0. testudinaria (Balm.) occurs, according to Mc Coy, at Carn 

 Grorran, so also does the 0. retrorsistria of Mc Coy, which is 

 perhaps a mere variety of the same fossil. 0. parva {Pander) 

 occurs both at Q-orran and Grreat Peraver according to the same 

 author, Davidson considers the latter to be part of Salter's 

 supposed 0. redux of Barrande (not the real 0. redux). He 

 looks upon the whole of them as varieties of his species 

 0. Budleighensis, which he gives as Llandeilo and Caradoc. In a 

 private communication he says, " I do not think that more than 

 5 species (i.e. of Orthis auct) can be admitted." 



Besides the above, fossils from Grorran Haven marked 

 0. furcifer and 0. virgulata alfe to be seen in the Jermyn Street 

 Museum. I do not know whether Mr. Davidson has seen these, 

 they were named by Major Wyatt-Edgell — a well-known 

 authority — who considered them to be of Arenig age. 

 Formerly there were in the same Museum fossils from Gorran 

 named 0. confinis and 0. vespertilio ; these names have of late 

 years very properly disappeared. 



Thus it will be seen that the brachiopods tell a similar tale 

 to the trilobites ; they are recognized — S. grandis through its 

 constant associate 0. calUgramma — as being species which are 

 quite as characteristic of the Llandeilo as of the Caradoc horizon. 



Other fossils from the Quartzytes and associated rocks. These 

 do not give much information on the subject, as they have not 

 yet been sufficiently compared and worked out. 



