Vol. 62.] 



LIMESTONE OF THE MENDIP AREA. 



325 



not permitted me to pay much attention to this part of the subject. 

 But to one of these problems, namely, the geology of the Ebbor-Rocks 

 district, a subject which has received attention from several previous 

 writers, I have devoted a considerable amount of time. The features 

 of this locality are especially interesting, and I have described them 

 in a separate note. 



Throughout the paper, I have adhered to the system of nomen- 

 clature of corals and brachiopods employed by Dr. A. Yaughan and 

 denned in the introduction x to his paper. The palseontological notes 

 and plates 2 accompanying Dr. Yaughan's paper, taken in conjunction 

 with the notes and plates which I have appended to the present 

 paper, will explain my faunal lists. 



Following the suggestion made 3 by Dr. Yaughan, I have adopted 

 the term Avonian to connote the whole Carboniferous-Limestone 

 Series, as developed in the South- West of England and South Wales, 

 and the terms Clevedonian and Kidwellian for the lower and 

 upper divisions, respectively, of the Avonian. The use of these 

 terms secures a highly-desirable definiteness, and avoids the possi- 

 bility of any confusion such as might arise from comparisons, based 

 on lithological divisions only, with the Carboniferous rocks of other 

 areas. The distinctness of the Clevedonian and Kidwellian faunas, 

 which is a well-defined feature in the Ifendips, as in the Bristol 

 area, is demonstrated in a separate note. 



The series of zones and subzones in the Avonian of the Hendip 

 area is as follows : — 



Zones. 



Subzones $ Horizons. 



Approximate 

 thickness in feet. 



^ j Dihunophyllum . 



B1 



g 1 Semimda 



f (D 2 ) Lonsdalia floriformis. 

 \ (D 1 ) Dihunophyllum 9. 



f (S 2 ) Productus aff. Cora, mut. S 2 . 

 < (S x ) Productus cf. semiretioula- 

 tus, inut. 8 r 



\ 500 

 I 720 



> 



63 

 O 



( Syringothyris . . . 



Zaphrentis 



Cleistopora 



(0) Syringothyris aff. cuspidata, 

 mut. C. 



>r< 



1 (Z.,) Zaphrentis aff. cormicopice. 

 \ (ZJ Spirifer aff. clathratus. 



>£< 



C (K 2 ) Spinferina cf. octoplicata. 

 \ (K x ) Productus bassus. 

 1 (M) (Modiola--pha$e.) 



550 



} 800 



I 450 

 3020 



1 Quart. Journ. Geol. Soc. vol. lxi (1905) pp. 183, 184. 



2 Ibid. pp. 266-303 & pis. xxii-xxvi. 



3 Ibid. p. 264. 



