Vol. 67.] THE CARBONIFEROUS SUCCESSION IN GOWER. 565 



Comparison with Athyris roissyi (L'Eveille). 1 — The figures 

 of L'Eveille's type depict a shell of more or less transverse form 

 with a large beak and perforation, a well-marked median fold and 

 strong distant growth-halts. If we accept the tacit assumption, 

 made by both L. G. de Koninck and T. Davidson, that the valves 

 were ornamented with fringed expansions (neither mentioned in 

 L'Eveille's text nor indicated in his figures), L'Eveille's species 

 can be well matched by the Z, form of ' Cliothyris glabristria ' in 

 the South-Western Province. This conclusion, if recognized, 2 

 would involve the following changes of nomenclature : — 



' A. glabristria, rout. Z 2 ' becomes A. roissyi (L'Eveille). 



' A. roissyi' of Km and Z becomes a new species, on account of its difference 

 of form and beak (see PL XLI, fig. 8 b). 



Athyris globularis stands, since it is differentiated from the 

 above forms by the closeness of its expansions and by the fact 

 that they are completely fringed. 



IX. Summary of Pal^ontological Sections. 



(a) The existence of a Modiola phase at the base suggests 

 conformity to the underlying Old Red Sandstone ; this conformity 

 has been demonstrated by Mr. Dixon in North-Western Gower. 



(6) The zones Z, C, Sand D contain faunal assemblages identical 

 with those of the same zones in the Bristol Area. 



It is, however, interesting to note that small Zajjhrentes of Lower 

 Avonian aspect are abundant just above the Caninia Oolite, in 

 association with Cyathopliyllum <p and Michelinia granclis. 



(c) The faunal evidence suggests that the lower limit of the 

 D 2 _ 3 phase lies within D 2 of Bristol, but that the upper limit of the 

 phase lies above that subzone and within the ' Millstone Grit ' of 

 the Bristol sequence. 



(d) The upper part of C 2 is so closely related faunally with the 

 overlying Lower Seminula Zone, that it is impossible to refer these 

 two subzones to different divisions of the Carboniferous Limestone. 



(e) The most important coral and brachiopod groups discussed 

 in the paper are : — 



Zaphren tis oystermouthensis. 

 Procluctus sulcatus and Productus costaUis. 

 Forms included in the group of Spirifer bisulcatus. 

 Athyris globularis and A. roissyi. 



I have received much help from the following geologists, and to 

 them I tender my heartiest thanks : — Mr. B. G. Carruthers, 

 Dr. Wheelton Hind, Dr. E. A. Bather, Mr. J. W. Tutcher, and 

 Mr. W. H. Wickes. 



1 Mem. Soc. Geol. France, vol. ii (1835) pi. ii, figs. 18-20. 



2 L. Gr. de Koninck was quite aware of the fact that Athyris roissyi had 

 been wrongly identified; but he suggested that no change should be made, in 

 order to avoid confusion. See Ann. Mus. Row Hist. Nat. Belg. vol. xiv, pt. 6 

 (1887) pp. 85. 86. 



