Il6 OLD RED SANDSTONE. 



Upper Devonian Sandstones (Pickwell Down Sandstones, etc.) may 

 with little doubt be grouped with the Upper Old Red Sandstone ; 

 the arenaceous beds of the Lower Devonian in North Devon 

 (Hangman Grits) yield some marine mollusca, and cannot perhaps 

 in this respect be so satisfactorily correlated with the Lower Old 

 Red Sandstone ; but it must be remembered that the Silurian 

 rocks merge gradually upwards into the Lower Old Red Sandstone, 

 and the Lower Devonian Beds of South Devon and Cornwall have 

 yielded some fish-remains of similar genera to those found in 

 the Lower Old Red Sandstone. 



The Devonian fauna, broadly speaking, includes many 

 species of Corals, belonging to the genera Favosites, Cyatho- 

 phyllnm, Petraia, Calceola, etc.; Polyzoa, incXndmg Fenestella ; 

 Brachiopoda of the gen^vdi Athyris, CJionetes, OrtJiis, Spirifera, 

 Stringoceplialns, and Uncites ; Lamellibranchs of the genera 

 Pterinea and Curtonotiis ; and Cephalopods of the genera 

 Clyvienia and Goniatites. Among Trilobites, the genera 

 Houialonotns, P/iacops, etc., are met with.^ Graptolites of the 

 genus Diciyograptus have been recorded from Devonian rocks, 

 but not in this country.^ 



The Upper and Lower Old Red Sandstone contain com- 

 paratively few fossils, and these are chiefly Plants, Crustacea, 

 and Fishes.^ 



OLD RED SANDSTONE. 



The name Old Red Sandstone was given in contradistinction 

 from the term New Red Sandstone, the latter group overlying 

 the Carboniferous strata ; while the former group, regarded 

 as a connected series, underlaid the same strata. The term 

 Old Red Sandstone was used by Conybeare in 1822, but the 

 rocks were first claimed by Murchison as a distinct system in 

 1839.^ 



The Old Red Sandstone consists of red and grey micaceous 

 and mottled sandstones, sometimes false-bedded, quartzose 

 conglomerates, slaty micaceous marls, and shales. Its name, 

 however, bespeaks its most prominent character. In some 

 localities bands of nodular or concretionary limestone called 



' See The Palaeozoic Fossils of Cornwall, Devon, etc., by John Phillips, 1841, 



^ Dr. O. Herrmann, G. Mag. 18S5, p. 407. 



^ See J- Powrie and E. Ray Lankester, The Fishes of the Old Red Sandstone 

 (Palseontograph. Soc. ). See also the Tlusaiirtis Devonko-Carbonifertis, by Dr. J. 

 J. Bigsby, 1878. 



* Silurian System. 



