RHYNCHONELLID. 181 
Dudley, and near Walsall, also at Benthall Edge, and it is stated to occur at Rock Farm, 
May Hill. Prof. M‘Coy mentions the shell as occurring in the black calcareous flags of 
Mathyrafal, south of Meifod, Montgomeryshire. I am not acquainted with it from either 
Scotland or Ireland. Dr. Lindstrém has obtained this shell at Gothland. 
RHYNCHONELLA NucuLA, Sow. (sp.). Pl. XXIV, figs. 1—7. 
TEREBRATULA NUCULA, J.deC.Sow. Silurian System, pl. v, fig. 20, 1839. 
—_— PUSILLA, Sow. Ib., pl. xxi, fig. 18, 1839. 
= NEGLECTA, Id. Ib., pl. xxi, fig. 14, 1839. 
a putcura, Id. Ib., pl. v, fig. 21, 1839. 
— Pome, Dav. Bull. Soc. Géol. Fr., 2nd ser., vol. v, p. 330, pl. iii, 
fig. 28, 1848. 
_ SEMISULCATA, Salter and Sow. Quarterly Journal Geol. Soc., vol. i, 
p- 21, 1843. 
Hyporuyris _ Phillips and Salter. Memoirs of the Geol. Survey, vol. ii, 
p- 382, pl. xxviii, figs. 1—8, 1848 = T. neglecta, Sow. 
Sil. Syst., pl. xxi, fig. 14. 
— nucuLA, Id. Ib., p. 281. 
HEMITHYRIS — M‘Coy. Brit. Pal. Foss., p. 204, 1852. 
RHYNCHONELLA — Morris. Cat. of British Fossils, p. 147, 1854. 
— — Lindstrém. Gottlands Brachiopod., p. 366, 1860. 
— on Salter. Memoirs Geol. Survey, vol. iii, p. 278, 279, and 
368, 1866. 
ATRYPA _ M‘Coy. Synopsis of the Silurian Fossils of Ireland, 
p- 40, 1846. 
RAYNCHONELLA — Salter. Siluria, 2nd ed., pl. xxii, fig. 1, and p. 250, fig. 57, 1, 
1859. 
—_— oBTUSIPLICATA, Id. Ib., 2nd ed., p. 545, 1859. 
Spec. Char. Shell small, subpentagonal, with rounded angles, more or less globose. 
Ventral valve less convex than the opposite one ; beak small, pointed, and incurved ; sinus 
wide, moderately deep, commencing about the middle of the shell, and extending to the 
front. Dorsal valve convex and often gibbous, mesial fold about as wide as a third of the 
breadth of the shell, much raised close to the front. Surface of each valve ornamented 
by from sixteen to twenty angular ribs, of which usually four occupy the fold, and three 
the sinus. ‘Two specimens measured— 
Length 5, width 6, depth 4 lines. 
shen Opies Gti ras eB ody 
Obs. This troublesome little shell has misled more than one paleontologist, and 
several names have been given to apparently simple modifications in shape of the Sowerbyan 
species. It seems to have been for the first time named, described, and figured, by 
J. de C. Sowerby, in the ‘Silurian System ;” but the figures are incomplete and unsa- 
