194 BRITISH SILURIAN BRACHIOPODA. 
the length of the valve; and on either side of this, on the bottom of the shell, are situated 
two muscular (adductor) impressions. 
Length 8, width 9, depth 4 lines. 
Obs. This beautifully sculptured shell was discovered by Mr. Capewell in 1847, and 
I shortly afterwards published a figure and description of the species from specimens I had 
picked up at Hay Head, near Walsall at about the same time. The sculptured surface is 
very peculiar, and nearly resembles that seen on Descina (Trematis) punctata. 'The cells (not 
punctures or perforations) vary much both in size and shape, are small at the umbone and 
on the beak, but gradually become larger as they near the middle of the shell, becoming 
again smaller asethey approach the frontal and lateral margins. When there has been an 
interruption in the growth of the shell, and which is indicated by a sharp concentric line, 
the cells often begin again by being smaller. They also assume a greater or lesser degree 
of regularity in their shape, some being almost triangular, lozenge-shaped, or more or less 
regularly five- or six-sided. On the valve of one specimen, measuring five lines in length 
by some six in breadth, I counted nearly three thousand of these cells. In some examples 
the mesial fold is hardly produced above the regular convexity of the valve, while in other 
examples it is sharply defined. No very satisfactory specimen showing the interior of this 
shell has been found; but an internal cast from Malvern, in the Museum of the Geol. 
Survey (fig. 15), exhibits some of its characters, and Prof. Hall assures me that the 
species is, without doubt, referable to the genus Lichwaldia. Whiie I was describing 
our British shell in 1848 M. de Verneuil showed me some specimens he had found in the 
Niagara group at Lockport, in America, which at the time appeared to me as well as 
to him to be identical with our &£. Capewelii. This American shell was afterwards 
described and figured by Prof. Hall in vol. 11 of his magnificent work on the ‘ Palzeontology 
of New York’ (p. 281, pl. lv, fig. 5, 1852), under the designation of Atrypa corallifera. 
A full description of this last-named species is to be found in the ‘Report of the State 
Cabinet for the Year 1865;’ and in Pl. XXV, fig. 13a, will be seen a section of the 
American shell, taken from Prof. Hall’s figure. 
Position and Locality. 'This species appears to be confined to the Woolhope and 
Wenlock formations. It occurs in the Wenlock Shale at Hay Head and Linley’s Lime- 
Works, north-east of Walsall; also at Dormington Wood and Dudley. It has also been 
found near the road between Alfrick and Crews Hill, Malvern, in beds of the Wool- 
hope age. I am not acquainted with the shell from either Scotland or Ireland, but it has 
been found in the Island of Gothland by Dr. Lindstrém. 
Eee 
