ROCKS OF THE FOREST OF DEAN. 213 



No. I. — Section of a portion of the Loiuer Limestone Shales 

 exposed in Quarry near Drybroolc, Forest of Dean. 



Petrology. ft. in. Chief Fossils. 



Not exposed. 



Blue limestone 3 Fossils scarce. 



Impure limestone 4 No fossils. 



Limestone 4 Athyris Roissyi. 



Argillaceous beds 8 Rhynchonella pleurodon. 



Limestone 7 Encrinites, R . pleurodon. 



Rhynchonella-bed 7 R • pleurodon abundant. 



Argillaceous and calcareous bands... 1 Encrinites in the calcareous bands. 



Limestone 5 Encrinites, Polyzoa. 



Argillaceous beds 1 4 No fossils visible. 



Polyzoa-bed, impure limestone ... 2 5 Polyzoa numerous, with a profusion 



of Ecrinites. 

 Limestone and beds of clay, not fully exposed. 

 Sandy beds 



To the " Polyzoa-bed " in the above section I desire to direct 

 special attention. It is a cream-coloured impure Limestone, crowded 

 with the stems of Poteriocrinites crassus (Miller), which have the 

 peculiarity of being insoluble in cold acid. There are also a few 

 Athyris Roissyi and spines of Productus ; but the most charac- 

 teristic fossils are three species of Polyzoa which are also common 

 to the E-ed Limestone of Arran *. 



The next bed of special importance in the above section is Ihe 

 one which I have termed the " Rhynchonella-bed." It is ku 

 argillaceous deposit, seven inches thick, and is characterized by the 

 number of Rhynchonellaz which occur in it. Specimens of these 

 shells were sent to Mr. Davidson, F.R.S., to whom I am indebted 

 for the determination of them ; he wrote to me saying that they 

 were a small variety of R. pleurodon " much crushed." Besides 

 these fossils, the bed contains Athyris Roissyi, fragments of per- 

 forated Brachiopod shells, spines of Productus, and a small Serpula. 

 There are also thin yellow- coloured disks, the larger ones avera- 

 ging about # 008 inch in diameter. Some of these resemble 

 sporangia ; but I leave the matter open for further investigation. 

 A sample of the bed was sent to Dr. Hinde, to whom I am under 

 an obligation for much kindness in giving me his opinion on 

 matters referred to him. Dr. Hinde saw signs of what appeared to 

 him to be fragments of the jaws of Annelids ; and he recommended me 

 to search further into the matter. This I did, and was rewarded by 

 finding one perfect specimen and several fragments ; and I now have 

 the authority of Dr. Hinde for saying that the jaws found are those 

 of Annelids. 



The whole of the Lower Limestone Shales is not exposed at 

 Drybrook ; and the same remark applies to the Mountain Limestone. 

 The close of the formation is represented by shales and limestone, a 

 part section of which I append ; it was taken many years ago by 

 Mr. Lucy, who has kindly given me permission to use it. 



* These fossils were submitted to Dr. Wright, F.R.S., and Mr. John Young, 

 of Glasgow, who kindly determined the species to be Rhabdomeson yracile, 

 Ferestella tuberculata, and Ceriopora similis. They were referred to by Dr. 

 Wright in an appendix to this paper. 



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