136 



BRITISH SILURIAN BRACHIOPODA. 



which need not be here repeated. Dr. Lindstrom informs us that to a variety of this 

 species Prof. Loven has given the MS. name of lamellosa. 



Position and Locality. Atrypa imhricata ranges from the Caradoc beds up to the 

 Wenlock Limestone. It is common in the Wenlock Limestone at the Wren's Nest, 

 Dudley, at Benthall Edge, Wenlock Edge, Hay Head, near Walsall, Woolhope, &c. At 

 Haverfordwest in Lower Llandovery beds ; at Guilsfield, north-west of Welshpool, in the 

 Upper Caradoc ; in the Bala beds of Keisley, near Dufton, in Westmoreland. In Scotland 

 it occurs in the Caradoc (?) of Penhill, In Ireland at Killey, Pomeroy, and the Chair of 

 Kildare, in Caradoc or Bala Limestone, Many more localities might be given ; but as 

 some confusion has taken place from the mixing of the two species, those localities only 

 where the shell is positively known to occur are here recorded. 



It occm's in Gothland ; and Prof. Schmidt states in his memoir already mentioned 

 that J. imhricata occurs in the Lower and Upper Silurian rocks of the Baltic Provinces, 

 It was also found in Bohemia by M. Barrande, in Etage E. 



Atrypa ? hemisph^rica, /. de C. Soic. PI. XIII, figs. 23 — 30. 



Atrtpa hemisph^rica, Sow. Sil. Syst., p. 637, pi. xx, fig. 7, 1839. 



_ _ M'Coy. Syn. Sil. Foss. Ireland, p. 39. 1846. 



Terebratula — Be Ferneuil. Bull. Soc. Geol. France, 2nd series, vol. iv, 



p. 654, 1847. 



Atrypa — Phillips and Salter. Mem. Geol. Surv. Great Britain, vol. ii, 



part 1, p. 277, 1848. 



— — Salter. Quart. Journ. Geol. Soc, vol. vii, p. 172, 1852. 



— — Hall. Palaeont. New York, vol. ii, p. 74, pi. xxiii, fig. 11 



a, g, 1852. 



Hemithyris — M'Coy. Brit. Pal. Foss., p. 201 (also var. Scotica, p. 202), 



1852. 



Ateypa — Salter. Siluria, 2nd edit., p. 100, fig. 4, and pi. ix, fig. 3, 1859. 



Leptoccelia — Hall. Report of the Regents of the University of the State 



Cabinet of New York, p. 33, 1857, and Pal. New York, 

 vol. iii, p. 448, 1859. 

 Atrypa — Salter. Mem. Geol. Surv., vol. iii, p. 36, 1866. 



Leptoc(ELIA — Billings. Catalogue of the Silurian Fossils of the Island of 



% Anticosti; Geol. Surv. of Canada, p. 48, 1866. 



Spec. Char. Shell small, sub-orbicular, usually wider than long ; ventral valve sub- 

 hemispherical, evenly convex ; beak small, pointed, incurved, with a foramen beneath it. 

 Dorsal valve very nearly flat and orbicular, slightly depressed along the middle ; sides 

 rounded ; frontal margin a little deflected. Hinge-line very obtuse, nearly as long as the 

 breadth of the shell ; with rounded cardinal angles. Surface of each valve ornamented 

 with from twelve to eighteen simple rounded or sub-angular ribs, with concave interspaces 



