Vol. 67.] THE CAKBONTFEROUS SUCCESSION IN GOWER. 545 



Z 2 : 



South-Western District : lihossili to Worm's Head 

 (indicated by 1). 



(This subzone is also exposed at Threecliff Bay in the Eastern 

 District ; the beds are, however, here dolomitized, and fossils are 

 indeterminable.) 



Corals : — 



Zaphrentis omaliusi i Ed. & H., Carruthers. 

 Zaphrcntis konincki- Ed. & H., Carruthers. 

 Caninia cornucopia Mich., Carruthers. 

 All three are common in 1. 



Brachiopods : — 



The usual Z. 2 assemblage : no list was drawn up. 



Horizon 7. 

 South-Western District: lihossili to Worm's Head (denoted 



by i). 



Corals : same as under Z 2 , together with : — 



Michelinia tenuisepta Ed. & H. and de Kon., non (Phill.). 

 Caninia cylindrica (Seouler in M'Coy) Vaughan. 3 



Brachiopods : — 



Productus cf. pustulosis 4 Phill. (and cf. Pr. christiani de Kon.). 



Semireticulate Productus. 



Leptcena. 



Orthotetid. 



Spirifer aff. clathratus M'Coy, Vaughan. 



Spirifer cinctus de Kon. 5 



Syringothyris cuspidata (Martin). 



Syringothyris cf. laminosa (M'Coy) (Dav. pars). Vaughan. 6 



1 — Z. aff. phillipsi Ed. & H., Vaughan : as described in ' Bristol Paper,' 

 p. 270. 



2 = Z. aff. cornucopia (Mich.) Ed. & H. : as identified in ' Bristol Paper.' 



3 Caninia cylindrica, as employed in the 'Bristol Paper,' covered all the 

 Caninias from the entrance of the genus at the top of Z 2 to the maximum 

 of 'C. cylindrica, mut. S x ,' in the Lower Seminula Zone. These would now 

 be differentiated into C. cornucopia, C. palula, and C. cylindrica with 

 variants of each ; at the time of our work in Gower (in 1905), however, all 

 these forms were lumped under C. cylindrica. 



4 A common form at several points of the South-Western Province and 

 first appearing in 7 : maximum at the top of C ] and in C 2 . The umbonal region 

 is strongly wrinkled and pustulose, but the skirt is often almost smooth 

 (cf. Productus christiani, which is abundant in C 2 of Belgium). 



o Spirifer cinctus Fischer is an Upper D form and a near ally of Sp. planicosta 

 (M'Coy) : the form cited above is referred to as Spirifer konincki Dewalque 

 by Belgian writers, and is an important zonal index of Z-C. 



6 The form here indicated accords with Syringothyris in its general build 

 and area, but is more closely allied to Spiriferina in its umbonal plates. All 

 Carboniferous Spiriferinas have a primitive syrinx which, however, remains 

 undeveloped and is buried in. and filled in by, the umbonal callus. In the 

 species here recorded, the syrinx is quite obvious, although confined to the 

 apical portion of the delthyrium. 



