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DR. A. VAUGIIAN ON THE PAL^ONXOLOGICAL [May I905, 



Dibun ophyllum-7iO\ie. 



(a) The lower part or ^-subzone is, so far as I know, unexposed. 



(b) The upper part or Lonsdalia-$ubzon&. 



Exposure. — In the large quarry now worked, on the southern 

 edge of the mass, immediately north of Wrington. 



Lithological character. — Massive limestones with some 

 shales, and rubbly limestones. 



Fauna: — 



Alveolites septosa. 



Syringopora cf. distans. 



Lithostrotion ensifer. 



Lithostrotion Martini and especially 



a mutation towards L. irregidare. 

 Lithostrotion Portlocld and var. 



M' Coyanuni. 

 CyathopJiyllum regium (simple and 



compound). 

 Cyatkophyllum Murchisoni (var.). 

 Lonsdalia floriformis and the var. 



cf. rugosa. 

 Olisiophyllids of three main types, 



namely : Dibunophyllum \p, Axo- 



phyllum 9, and Koninckophyllum 0. 

 Seminula aff. ficoidea (scarce). 



Spirifer cf. grandicostatus (cf. David- 

 son, ' Monogr. Brit. Paleeoz. 

 Brachiop.' Palaeontogr. Soc. pi. vii, 

 fig. 8). 



Spiriferina (?J cf. integricosta ((._.- 

 Davison, pi. ix, fig. 16). 



Beticidaria lineata. 



Camarotoechia pleurodon (cf. Davidson, 

 pi. xxiii, fig. 2). 



Productus aff. Cora (mut.). 



Productas hemisphericas. 



Chonetes sp. 



Avicidopecten sp. 



Fenestellids. 



Fistulipora (1). 



Notes. — The Wrington quarry is now the best exposure in the Bristol 

 area, from which to collect the corals of this subzone. The coral-fauna is 

 identically that of the same horizon in the Avon section, as exhibited in the 

 exposures on the river-side of Stokeleigh Camp, in the quarry on Eownham 

 Hill, and at Bound Point on the Clifton side of the river. 



The brachiopods and lam elli bran chs occur crushed in a thin shale, 

 consequently their determination is a matter of considerable difficulty and 

 uncertainty. 



A curious form of Fenestellid is met, with, both at Wrington and at 

 Round Point. 



I have now completed the detailed account of the several zones, 

 as they are displayed in the different parts of the Bristol area. 

 Before proceeding to compare the zonal sequence in the Bristol 

 area with that in other districts, it will be necessary to compile a 

 table of the commonest corals and brachiopods, which shall show 

 the range and maximum of each species-group (or gens) throughout 

 the zonal sequence adopted in this paper for the Bristol area. By 

 comparing this table with similar tables for distant areas, it will 

 be possible to plot accurately the directions and amount of the 

 great geographical variations in relative sequence, which the 

 different species-groups undergo. 



The smaller variations, which take place within the Bristol 

 area itself, have been noticed here and there in the detailed 

 description of the different parts of that area, and the importance 

 of such observations, when completed, has been pointed out in the 

 Introduction (p. 185). 



