122 



BRITISH SILURIAN BRACHIOPODA. 



Position and Locality. It occurs plentifully in the Lower Ludlow rock at Mathon 

 Lodge, west flank of Malverns ; also at Dog Hill, Ledbury. The type specimen of this 

 species, as well as that of A. compressa, Sow., may be seen in the Museum of the Geo- 

 logical Society of London. 



M. Barrande found this species near Prague, in Bohemia. 



Athyris compressa, Sow. (sp.). PI. XII, figs. 16 — 18. 



A.TRYPA COMPRESSA, 8ow. Sil. Syst., pi. xiii, fig. 5, 1839. 

 _ _ WCoy. Syn. Sil. Fo6s. Ireland, p. 39, 1846. 



? Terebratula, — Barrande. Silur. Brach. Bohmen, p. 47, pi. xiv, fig. 3, 

 1847. 



— — Bav. Bull. Soc. Geol. France, 2nd ser., vol. v, p. 327, 



J848. 



Rhynchonella — Suiter. Siluria, 2nd edit., p. 544, pi. xxii, fig. 22, 1859. 

 1 Spieigeba — Lindstrdm. Ofvers. K. Vet.-Akad. Forhandl., p. 361, 



1860. 



Spec. Char. Shell small, orbicular, somewhat transversely oval or circular ; valves 

 moderately and nearly equally and evenly convex, rather compressed, without fold or 

 sinus ; front line slightly rounded on the margin ; beak in ventral valve very small, and 

 much incurved over the umbone of the opposite valve, so that the minute aperture is but 

 rarely exposed. Surface smooth, marked more or less deeply with concentric, slightly 

 projecting lines of growth ; shell-structure fibrous, not punctured. 

 Length 5^, width 6, depth 3 lines. 



Oh. I have stated my reasons above (p. 121) for thinking that this and A. obovata 

 may probably belong to a single species. In one or two examples a shallow or slight 

 median depression was observable near the front, as may be noticed in a specimen from 

 Dudley, in Gray's collection, British Museum (fig. 17). Although I have not been able 

 to examine the interior of any of our British examples, it is very probable, if not certain, 

 that the animal was provided with spiral lamellae for the support of its oral arms ; and if 

 the specimen figured by M. Barrande from Bohemia be really referable to the shell 

 under description, we possess positive evidence of their occurrence. Mr. Salter, at 

 p. 544 of 'Siluria,' 2nd edit., places A. conqjressa in the genus Rhynchonella; and at 

 p. 542 A. obovata, doubtfully, in Athyris. I think, however, that they both belong to the 

 same genus, if not to the same species. 



Position and Locality. A. compressa occurs in the Wenlock limestone near Dudley, 

 and the Woolhope limestone at Woodside and Nash, Presteign ; also in the Upper 

 Silurian (Wenlock) shales of Hare Hill, in the Pentland Hills. In Ireland M'Coy 

 thought he obtained it from the Lower Silurian schists of Tii'naskea, Pomcroy, Co. 



