BRITISH SILURIAN BRACHIOPODA. 155 



42. Rhynchonella Girvaniensis, Bav. Sil. Sup., PI. X, figs. 26, 26 «. 



Shell almost circular or as wide as long ; dorsal valve convex and ornamented vs^ith 

 about thirteen angular ribs, of which the three largest form the mesial fold. 

 Length 3 lines by a little more in breadth. 



Ohs. — Of this small species Mrs. R. Gray unfortunately found only one dorsal valve 

 in the Upper Llandeilo or Balcletchie Conglomerate of Balcletchie, in Ayrshire. It 

 somewhat approaches to Rli. nucula. I have given it a name for reference, as all the 

 species from the Upper Llandeilo are important to recognise. 



43. Rhynchonella Glassii, Bav. Sil. Mon., PI. XII, figs. 11—15; and PI. XIII, 



fig. 6 ; Sup., PI. X, figs. 22, 22 a. 



Atrtpa depressa, Sow. Sil. Syst., p. 629, pi. xiii, fig. 6, 1839. 

 Rhynchonella depressa, Morris. Catal. Brit. Foss., 2nd edit., p. 146, 1854. 

 Athyris 1 (Rhynchonella), Salter. Siluria, p. 524, pi. xxii, fig. 17, 1859. 



— — Dav. Sil. Mon., p. 123, pi. xii, figs. 11— 15, and pi. 



xiii, fig. 6, 1866. 



Morris, Salter, and M'Coy were correct when they referred the so-called Atryjja 

 depressa, Sow., to Hhynchonella^ but they were not acquainted with its interior, and I 

 myself felt very uncertain as to the genus to which Sowerby's shell should be referred. 

 Having received some typical examples from the Woolhope Limestone and road between 

 Alfrick and Crew Hill, Malvern, the Rev. N. Glass was able to develop their interiors, 

 and to clear away all uncertainty as to the generic position of the shell, for it has the 

 two short curved lamellae of the genus Bliynchonella, as may be seen from the figure, 

 drawn from one of Mr. Glass's worked specimens, in PI. X, fig. 22 a. 



As Sowerby had in 1825 applied the name depressa to a Cretaceous Rhynchonella 

 ('Min. Con.,' vol. v, p. 165, tab. 502), we are compelled to give anew name to the 

 Silurian form, and could not find a more appropriate one than that of Glassii, as the Rev. 

 N. Glass was the first to show that the shell was possessed of the internal characters of 

 the genus Bhynchonella. See also above, page 134. 



