544 MR. E. E. L. DIXON AND DE. A. VATTOHAN ON [Nov. 19I I 



LOWEK AVONIAN. 



Cleistopora Zone (K). 

 South-Western District : 

 Km: 

 Only the base of K is exposed near Rhossili. 



Braehiopods : — 



Chonetes cf. crassistria Vaughan r (non M'Coy). 

 Eumetria aff. carbonaria (Dav.) Vaughan. 2 

 Camarot&chia cf. mitcheldeanensis Vaughan. 



Lamellibranchs : — 



Modioliform species, including Modiola cf. lata. 



Gasteropods : — 



A small species of Bellerophon is common. 

 Ostracods. 



Zaphrentis Zone (Z). 

 Zj: 



Eastern District: Threecliff Bay (indicated by the 

 numeral 4). 



South-Western District : B-hossili to Worm's Head 

 (indicated by 1). 



Corals : — 



Small simple Zaphrentis — 1 and 4 (rare), 



Braehiopods : — 



Productus bur iin gtonen sis Hall, Vaughan — 1 and 4. 



Small Chonetes : [Ch. cf. crassistria predominating] — 1 and 4. 



Leptcena — 4. 



Orthotetid — 1 and 4. 



Spirifer aff. clathratus M'Coy, Vaughan — 1 and 4 (abundant; 



A small Syringothyris (cf. 8. typa Winchell) — 4. 



Reticularia cf. lineata 3 (Martin) (Dav.) — 1 (rare). 



Athyris (Cliothyris) cf. glabristria (Phill.) (Vaughan) — 4 (rare). 



Camarotcschia mitcheldeanensis Vaughan — 1. 



Crinoids : — 



Dichocrinus sp.— 4. (Determined by Dr. F. A. Bather, F.R.S.) 



1 ' Bristol Paper,' pi. xxvi, fig. 2 ; also Q. J. G. S. vol. lxiii (1907) p. 458. 



2 ' Bristol Paper,' p. 302. 



3 This species differs very considerably from Martin's figure in the irregular 

 and undulatory concentric wrinkles and in the prominence of the thick 

 underlayer of close-set tubes from which the fringed bands composing the 

 outer layer are formed. 



