326 MR. T. F. SIBLY ON THE CARBONIFEROUS [May I906, 



My sincere thanks are due to those geologists who have so readily 

 assisted me in my investigations. To Dr. A. Vaughan I am indebted 

 for continual encouragement, and especially for invaluable advice 

 throughout my paheontological work. I am indebted to Mr. H. E. 

 Balch for very kindly placing his knowledge of the Wells district 

 at my service, and particularly for the great assistance which he 

 has given me in the examination of the Ebbor-Eocks district. I 

 have to thank Dr. Wheelton Hind for naming lamellibranchs and 

 gasteropods; and Prof. S. H. Reynolds and Mr. E. P. Burt for 

 valuable assistance in the field. To Mr. J. W. Tutcher I am under a 

 deep obligation, for the trouble which he has taken in the preparation 

 of the excellent photographs (reproduced in Pis. XXXI & XXXII) 

 illustrating this paper. 



II. The Eattnal Sequence in the Mendip Area. 



Clevedonian or Lower Avonian (Lower Carboniferous 

 Limestone). 



K = Zone of Cleistopora aff. geometrica [CzEisTOPOEA-Zone] 

 (including Mo dio /a-phase M). 



General lithological character.— Shales with subsidiary 

 limestones in the lower part ; thick shales in the middle part ; 

 alternating shales and limestones in the upper part. 



Coral-fauna: 



Cleistopora aff. geometrica. 



Brachiopod-fauna : 



Athyris Boyssii muts. , Orthothetes aff. crenistria, muts. 



A 'fn'iiwi Q f Az-tftsn r\nr\nis*lim l? \ <-»r 7 rt.i'n /> 77 ncsv 1 h?h?'-r\>}/-7nw)/>77ri <-» 4+ ll^'yr'Ji/y/i/iil 



Bhipidomella aff. Michelini. 

 Productas bassus. 

 Productics cf. Martini. 



Chonetes ' Buchiana ' 

 Chonetes cf. crassistria 



Chonetes cf. hardrensis. 

 (Biscina) sp. 



& inter- 

 mediate 

 forms. 



Athyris (Actinoconchus) ctlame llosa. 

 Beticularia, cf. reticulata. 

 Spirifer aff. clathratus & var. 

 Spirifcrina cf. octoplicata. 

 Syringothyris aff. cuspidata, mut. K 

 Eumetria aff. carbonaria. 

 Camarotcechia mitcheldean ensis. 

 Beptcena analoga. 



Other groups : 



Lamellibranchiata. I Bryozoa. 



Modioliform lamellibranchs. Bhabdomeson spp. 



Barallelodon sp. Fenestellids. 



Gasteropoda, Ostracoda — several forms. 



Bellerophon sp. i 



Capulus cf. inoBquo.lis. 



Subdivisions : — 



M = Modiola-Tph&se. 



This includes only the lowest part of the series, and exhibits the 

 gradual establishment of the Cleisto]pora-i&\m&. 



