SPIRIFERA. 151 



broken off aslant, rows of fine comb-like spines like those of Athyris Eoyssii are 

 distinctly visible. Now Gosselet and Hall (for instance) distinguish A. concentrica 

 by its want of such spines, and that seems to be the general character of the shells 

 that are recognised as belonging to that species. Hence we may certainly conclude 

 that our shell is not A. concentrica, but some species of the sub-genus Cleiothyris to 

 which A. Royssii belongs. 



From the great distortion of the specimens, and their preservation only as 

 moulds, it is not easy to compare it with Carboniferous examples of A. Royssii. 

 It seems, perhaps, to differ in the spines being generally smaller, and the striae 

 being more numerous and becoming more crowded marginally ; but it evidently 

 itself varies in these points, and A. Royssii must have been equally variable, as 

 Davidson says that he has counted eighty striee on a moderately sized specimen, 

 whereas those he figured must have had fewer. The figure of the Irish A. depressa, 

 M'Coy, which Davidson identifies with A. Royssii, appears almost exactly like our 

 shells ; and Gosselet records A. Royssii from the Famennian of Belgium, with which 

 Dr. Barrois, in his visit to Devonshire last summer (1896), classed the Pilton 

 Beds. Therefore, though I formerly thought that the larger specimens of our 

 shells might be distinguished, I feel now no difficulty in regarding them as 

 A. Royssii, though possibly they may prove to be a local variety of it. 



Affinities. — Athyris reticulata, Gosselet, 1 is said to be distinguished from 

 A. Royssii by its smaller size, and by its width being greater than its length. In 

 these respects it may not differ from our shell, but it may perhaps have had a 

 stronger and more angular fold. 



2. Genus— Spirifera, Soiverby, 1815. 

 1. Spirifera microgemma, Phillips. Plate XVIII, figs. 7, 7 a, 8. 



1841. Spirifera microgemma, Phillips. Pal. Foss., p. 68, pi. xxvii, figs. 116 a, l. 

 1864. — lineata ?, Davidson (pars). Brit. Foss. Brach., vol. iii, p. 43, 



pi. iv, fig. 16 (only). 

 1882. — — — Ibid., vol. v, p. 32, pi. ii, figs. 5, 5 a. 



1896. — Whidborne. Proc. Geol. Assoc, vol. xiv, p. 375. 



Localities. — In the Porter Collection are six specimens from Pilton and one 

 from Roborough ; in the Barnstaple Athenseum two from Upcott, one from Top 

 Orchard, and one from Vicarage Well; in the Woodwardian Museum one from 

 Barnstaple. 



Remarks. — Davidson seemed inclined to regard Sp. microgemma, Phillips, as 

 1 1877, Gosselet, ' AnD. Soc. Geol. Nord,' vol. iv, p. 312, pi. iii, fig. 3. 



