DEVONIAN AND OLD RED SANDSTONE SYSTEM 209 



juv full of Tentaculites, Styliola, and Buchiola retrostriata, and 

 rti tain beds have yielded species of Orthoceras, Bactriteg, Tornocerag, 

 Mimoceras, Anarcestes, and Agoniatites with remains of Phacops 

 latifrons, P. granulatus, and P. Icevis. 



The variegated slates contain Entomis serrato-striata and 

 Posidonomya venusta, and they occupy a syncline which forms an 

 oval area around St. Minver and St. Kew. 



Nothing which exactly corresponds to the Petherwyn fauna has 

 been found on or near the coast, and it ia thought that ite strati- 

 graphical position is above that of No. 5 ; its absence in the west 

 being due either to an overlap of the basal Carboniferous Beds or 

 to faulting. 



In North Devon, on the other hand, there appears to be a 

 a mi] ilft c Mirivssion, and the difficulty is to determine where the 

 line of division between the two systems should be drawn. 



The series has been divided into three stages, the lowest being 

 the Pickwell Down Beds, a set of red, purple, brown, and green 

 s-iinNtuuf.s with intercalated bands of shale. They are traceable 

 from Pickwell Down near Morte Bay to Wiveliscombe in 

 Somerset, but the only fossils yet found are fish remains and fossil 

 wood. 



The Baggy Beds consist of green shales and yellowish sandstones 

 and flags, and extend inland from Baggy Point, north of Croyde 

 Bay, by Marwood and Sloly, where are quarries from which many 

 fossils have been obtained, including Ptychopteria damnoniensis, 

 Cucullfna unilateralis t Rhynchonella laticosta, Spirifer Verneuilli, 

 Stropiuilosia productoides, Chonetes hardrensis, and plant, remains 

 (Stigmaria and Knorria). 



The Pilton Beds consist of bluish-grey slates with thin bands 

 of limestone and of sandstone. They stretch from Croyde Bay 

 inland by Braunton and Pilton and are highly fossiliferous, con- 

 taining among others Phacops latifrons, Productusproslongus, Spirifer 

 Verneuilli, S. Urei, Orthis interlineata, Strophalosia productoides, 

 Aviculopecten nexilis, Loxonema anglicum, and other Gastropoda. 

 They appear to pass upward into the Lower Carboniferous shales, 

 and the divisional line has not yet l>een fixed ; but this point will 

 be discussed on a later page. 



2. The South of Ireland 



The Devonian rocks of Southern Ireland have generally been 

 treated under the head of Old Red Sandstone, but the more 

 complete knowledge which we now possess of their equivalent* in 

 Devon, Cornwall, and Brittany makes it probable that they arc 



P 



