164 



BRITISH SILURIAN BRACHIOPODA. 



Rhynchonella cuneata, Dolman and Hisinger (sp.). PI. XXI, figs. 7 — 11. 



Tebebratula ctjneata, Dalman. K. Vet. Akad. Handl., p. 141, pi. vi, fig. 3, 1827. 



— — Hisinger. Bidrag till Sveriges Geognosi, part iv, p. 239, 



pi. vi, fig. 3, 1828. 



— — Id. Lethaea Suecica, p. 81, pi. xxiii, fig. 5 a, b, 1837. 



— — Angelin. Mus. Pal. Suec, 1838. 



— . — J.deC. Sow. Sil. Syst., p. 625, pi. xii, fig. 13, 1839. 

 Atrypa — M'Coy. Synopsis of Sil. Foss. of Ireland, p. 39, 1846. 

 Terebratula — Be Ferneuil. Note sur le parallelisme des DepSts Paleo- 



zoiques, Bui. See. Geol. Fr., 2nd ser., vol. iv, p, 698, 1847. 



— — Barrande. Silurische Brach. aus Bohmen ; Natur. Abhandl., 



vol. i, p. 80, pi. xvii, fig. 11, 1847. 



— — Davidson and De Ferneuil. Bull. Soc. Geol. Fr., 2nd ser., 



vol. V, pp. 331 and 346, 1848. 



— — Bronn. Index Pal., p. 1233, 1848. 

 Spiriferina — B'Orb. Prodrome, vol. i, p. 42, 1849. 



Htpothyris — Phillips and Salter. 'Mem. Geol. Survey, vol. ii, part 1, 

 p. 280, 1848. 



Terebratula — Salter. Quart. Journal Geol. Soc, vol. vii, p. 172, 1851. 

 Atrypa — J. Hall. Palaeont. New York, vol. ii, p. 2/6, pi. Ivii, fig. 4 a — r, 



1852; Rhynchonella cuneata, 12th Annual Report of the 

 Regents, &c., p. 77, 1859. 

 — — Morris. Catalogue of British Fossils, p. 132, 1854. 



Retzia — Salter. Siluria, 2nd ed., pi. xxii, fig. 8, 1859. 



Rhynchonella — B' Eichwald. Lethsea Rossica, vol. i, p. 765, 1859. 



— — Undstrom. Ofv. K. Vet. Akad. Forhandl., p. 365, 1860. 



Spec. Char. Triangular or cuneiform, longer than wide, broadest anteriorly, or near 

 the front, posteriorly tapering into an almost angular beak. Valves usually depressed or 

 moderately convex ; beak of ventral valve more or less elongated or produced ; foramen 

 circular, placed under the extremity of the slightly incurved beak, margined, and 

 separated to a greater or lesser extent from the hinge-line by a deltidium in two pieces ; 

 lateral portions of the beak much depressed, forming broad, flattened, and slightly 

 concave spaces, which extend to fully half the length of the shell or more ; sinus wide 

 and shallow, commencing at a short distance from the beak, and extending to the front. 

 Dorsal valve somewhat deeper or more convex than the opposite one, flattened at the 

 umbone, but soon after forming a slightly raised broad mesial fold, which extends to the 

 front. Surface of each valve ornamented with from ten to fourteen angular ribs, of which 

 four or five compose the fold, while three or four occupy the sinus, the surface being also 

 regularly crossed by numerous fine, nearly equidistant, slightly raised, concentric lines or 

 ridges. Two specimens measured — 



Length 1 1, width 9, depth 6 lines. 

 10 „ 9 „ 6 „ 



