Vol. 67.] THE AVON I AX OF BUKKINGTON COMBE. 369 



Syr ingot ki,r is cuspidata (Martin) : the large C form. 

 Seminula of. ambigua (Sow.) : a distinct variant or new species. Com- 

 mon at a level discovered by Dr. Sibly. 

 Seminula I gregaria (M'Coy) (a doubtful reference). Not uncommon. 



[Gasteropods are abundant at certain levels: — Euomphalus and 

 Bellerophon. ] 



We here notice the initiation of two important Visean gentes, 

 Cyathophyllum aff. murchisoni (represented by its progenitor C. <p) 

 and Carcinophyllum 6 (leading on to Lonsdalia), as well as the 

 establishment of Productus aff. corrugatus and of Seminula ; 

 the last-named genus is represented by two peculiar species that 

 have a greater importance in the North-Western Province — now 

 for the first time sinking beneath the Carboniferous Sea. 



C,: 



Upper portion : the White Oolite. 



Corals : — 



Cyathophylkim <p Vaughan : typical form. 

 Chatetes (?) tumidus (Phill.) E. & H. 



Brachiopods : — 



Productus corrugatus M'Coy, mut. C . 

 Productus 9 Vaughan. Very abundant at the top. 

 Productus cf. sublavis de Kon. Rare. 

 Productus cf. concinnus Sow. Common. 



The rare sublcevis-like forms of Productus merely suggest their 

 enormous abundance at this level in Belgium and Northern France. 

 The "White Oolite is remarkably constant in position and fauna, 

 wherever the peculiar conditions of the Seminula Zone are about to 

 follow (Belgium, Northern France, South-Western Province, North- 

 Western Province.) In certain areas, however (as, for example, 

 South Pembrokeshire), the whole of C 2 is faunally continuous with 

 the Lithostrotion Beds above, and it is best to class C and S T 

 together as one division — the C-S Zone. On the other hand, in 

 areas where the Waulsortian or knoll phase is developed (parts of 

 Belgium and Ireland), it is often very difficult to separate C l from C . 



Seminula Zone (S). 



S,= 



Corals : — 



Lithostrotion martini E. & H. Common. 



Carcinophyllum mendipense Sibly. Not uncommon. 



Productiis corrugato-hemisphericus : a group composed of more than 



one gens. 

 Spirifer cf. suavis de Kon. (?). 

 Athyris cf. expansa Dav., non (Phill.). 



Atkyris cf. paradoxa (M'Coy). Not rare : very broad fringes. 

 Athyris in gens de Kon. 

 Seminula sp. Rare. 

 Camarophoria isorhyncha (M'Coy). Rare. 



