182 BRITISH SILURIAN BRACHIOPODA. 
tisfactory ; and this may partly account for the uncertainty, confusion, and difference in 
opinion which have existed about the subject. Sowerby, however, states his shell to be 
“@Globose, obscurely three-lobed, plaited; plaits sharp, about fifteen, three or four of 
which are prominent, and elevated in the middle of the front ; beak small, adpressed ; 
lower valve slightly flattened. Length 5 limes, width the same. oc. Ludlow, Presteign, 
Ledbury, Bagbarrow Hill, and west of Malvern Hills; Bradnor Hill, Kington ; Trewerne 
Hills, Radnorshire; Aram, near Newnham ;” and in Pl. XXIV, fig. 1, I have reproduced 
the original figure. In 1848, from my not understanding Sowerby’s species, I described 
under the name of Z. Pomelit some similar shells which I had found in the Aymestry 
Limestone at Sedgley and the Wenlock Limestone of Dudley. In the same year Phillips and 
Salter again described RA. nucula under the designation of Hypothyris semisulcata, Dalman. 
But I am not aware that Dalman ever gave that name to any Silurian species; it is cer- 
tainly not to be found in his “ Memoir on the Brachiopoda of Sweden,” published in the 
‘Transactions of the Royal Academy of Stockholm.’* Since then, however, both Mr. Salter 
and Prof. M‘Coy have placed //. semisulcata among the synonyms of &/.nucula. In their 
description Prof. Phillips and Mr. Salter observe—“ The above specific character, though 
long, is necessary to distinguish this common shell from other Silurian species, and espe- 
cially from 7. Jacunosa, with which Mr. Sowerby had cautiously united it. It is, 
however, a much smaller and more delicate shell, never has the strong ventral and dorsal 
sinus in the young state, and the middle does not rise abruptly and bring its plaits to 
a level as in 7' dacunosa (they mean 7. borealis], but has them on the sides, as well as 
top of the curved elevation ; the sinus is very deep on the front margin, but it is more by 
suppression of the central ribs than by their elevation, a very frequent character of 
Terebratule. The name is adopted from a Swedish specimen so labelled, but from what 
work of Dalman’s it is adopted we do not know. We recognise 7. neglecta, from the 
Lower Silurian rocks of Llandovery, for this species; it occurs at other places in Lower 
Silurian rocks.” Now, with reference to 7. neglecta, Sow., it may or may not possibly 
be a synonym of RA. mucula. It was observed and described by Mr. J. de C. Sowerby on 
a single incomplete or distorted fragment from Mandinam, Llandovery (Upper Llando- 
very), and is said to be “orbicular, convex, plaited; plaits 17, acute; beak small; a 
fragment.” In Pl. XXIV, fig. 17, will be found a figure drawn from the original specimen; 
and as I really do not know what to make of the shell, it may at least for the present be 
allowed to remain where Prof. Philips and Mr. Salter have placed it. 
In 1852 Prof. M‘Coy, while describing RA. nucula, observes—‘“ Having carefully 
examined a large number of specimens, I think with Prof. Bronn that the 7. pulchra 
and 7. nucula of Sowerby should be united, the very trifling differences in form and 
number of lateral plaits not coexisting, sometimes the one, and sometimes both, being 
observable in the contiguous specimens, which are clustered in great numbers in the 
' The name appears first in a paper by Salter and Sowerby, in vol. i, p. 21, of the ‘Quarterly Journal 
of the Geol. Soe. of London,’ 1843. 
