114 



BRITISH SILURIAN BRACHIOPODA. 



T. canalis or to Dalman's T. (?) didyma ; and I think the valve attributed to T. canalis by 

 M. de Verneuil in the great work on Russia (PL IV, fig. II) must belong to another 

 species. Hemithjris upsilon of M'Coy, from Pwllheli, appears to be Meristella didyma. 

 [Salter.] 



Meristella didyma varies in shape, as may be seen in the series of specimens figured in 

 our Plate; but is always easily distinguishable from J/, tumida, M. anyustifrons, and 

 M. Circe, on account of the furrow which in most specimens divides the valves into two 

 distinct lobes. It has neither fold nor sinus. 



Position and Locality. Meristella didyma occurs in the Llandovery, Wenlock, and 

 Ludlow Rocks. In the Upper Llandovery at Glansevin, Llandeilo. In the Wenlock 

 Limestone of Dudley. At Hay Head, Rushall Canal near Walsall, Benthall Edge, and 

 Ledbury. Wenlock Shale of Falfield, Tortworth. In the Upper Llandovery of Eastnor 

 Park, Malvern, and May HiU; and also at Pwllheli (as Hemithyris njjsiloti), according to 

 Mr. Salter. At Usk, Abberley, and Sedgley, in the Aymestry Limestone. Ledbury, 

 Herefordshire, in Wenlock Limestone. Messrs. Phillips and Salter found this shell at 

 Ridge Hill, Abberley district, in Aymestry Limestone : South-west of Hazle and Wootton 

 Earm (Woolhope district) ; at Llangibby ; and North of Camp Wood in Aymestry 

 Limestone; and at Dowlas in LoAver Ludlow (Usk district). Cwm-craig-ddu, Upper 

 Ludlow (Builth district). North of Trichrug. Storm Hill Lodge. Pont-ar-y Llechau, and 

 Golden Grove, Dafaddfa-Uchaf, in the Llandeilo district. On the Continent it occurs at 

 Ostergan, Gothland, at Solva (Ural), and in several localities in Oesel and Ehstland. 



Meristella nitida, Hall (sp.). PI. X, figs. 28 — 32. 



Tebebratula. L^viuscuLA, Sow. Sil. Syst., p. G31, pi. xiii, fig. 14, 1839. 



Atrypa nitida, Hall. Report Fourth Geol. District New York, pi. xii, fig. 5, 



1843 ; and Palaeont. New York, vol. ii, p. 268, pi. Iv, figs. 1 a—o, 



1852. 



Tekebratula l^viuscdla, Bronn. Index Palseont., p. 1240, 1848. 



— nitida, Dav. Bull. Soc. G6ol. Fr., 2nd ser., vol. v, p. 32", pi. iii, fig. 



37, 1848. 



— — De Verneuil. Ibid., p. 346. 

 Atrypa — UOrb. Prodrome, vol. i, p. 40, 1849. 

 Terebeatula? L.a;viuscuLA, Salter. Siluria, 2nd edit., pi. xxii, fig. 14, 1859. 

 Rhynchonella nitida, Id. Ibid., p. 545, 1859. 



Spirigera? — Lindstrom. Ofv. K. Vet. Akad. Forliandl., p. 361, 1860. 



/Spec. Char. Shell small, ovate, longer than wide ; valves almost equally convex : 

 beak small, incurved over umbonc of dorsal valve ; no foramen observable ; greatest width 

 of shell about the middle, broadest anteriorly, tapering to the extremity of thi' 

 beak. Valves almost etjually and moderately convex; lateral and frontal marginal line 



