230 



SUPPLEMENT TO THE BRITISH 



named varieties found in each of the British divisions of the Jurassic system we find 

 as follows : 



The Lias. 



In the Lower Lias about 23 species and 1 named variety. 



„ Middle Lias „ 60 ,, „ 5 or 6 varieties. 



,, Upper Lias ,, 29 „ ,, 1 or 2 ,, 



Of these, nineteen to twenty are common to two or three of these great divisions of 



the Lias, while four or five only have been hitherto shown as positively passing from the 



Lias into the Oolites. It is, however, probable that, when better known, a larger number 



may be discovered. It was during the deposition of the Middle Lias that the Brachio- 



poda were both specifically and individually most numerous. The Liassic deposits have 



been divided by different geologists and palaeontologists into a certain number of Zones 



characterised by certain species of Ammonites. Mr. R. Tate in 1869, in the ' Geological 



Magazine/ vol. vi, 1869, distributed the British Liassic Brachiopoda, that were known 



to him at the time, into Zones to which we have already referred. This mode of 



proceeding, as a matter of detail, is of great importance, and it should be proceeded with 



for the species in those localities where the sequence of zones is fairly represented. As 



an example of what can be done in this direction by local geologists, I have appended 



a table prepared with great care, at my request, by the Rev. F. Smithe, in which he has 



noted the range and distribution of each Liassic species in the zones so well represented 



in the Lias of Churchdown, in Gloucestershire, and I have myself verified his and my 



own identification. 



Species of Brachiopoda found by the Rev. E. Smithe in the Lias of Churchdoion 



and its neighbourhood. 



Zones. 



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CO • — 



(Tretenterata) — 



Lingula Metensis, Terquem 









X 



X 





X 



V 



X 



X 



x 





X 



X 













(Clistenterata) — 

 Terebratula punctata, Sow 

















X 





















„ Kadstockensis, Davids 

















X 





X 



■ 

 ■ 

 ■ 



■ 



X 



,, Edwardsi, Davids 

















„ globulina, Davids 





















Waldheimia perforata, Piette 





X 



...... 





X 







X 







,, indentata, Sow 





| 























X 









1 









1 









