DISCINIDA. 65 
Ludlow, Shropshire, &c. It has often been found in Wenlock shale near Dudley, 
and it occurs also in the Upper Ludlow rock, Ledbury. Mr. Lightbody has collected 
D. rugata in the Upper Ludlow of Whitecliffe and Sunny Bank, near Ludlow, and in 
the Lower Ludlow of Church Hill, where it is associated with Lingula lata. 
? Discina peRRueata, M‘Coy. Pl. V, figs. 19—24. 
ORBICULA PERKUGATA, M‘Coy. Synopsis of the Silurian Fossils of Ireland, p. 24, 
pl. iii, fig. 2, 1846. 
Prof. M‘Coy describes this species (?) as “nearly orbicular, depressed; about one 
sixth wider than long; apex one third the diameter from the margin; surface strongly 
wrinkled concentrically.” He adds, “This species is distinguished from the O. rugata, 
Sow., and O. plana, Minst., by the greater distance of the apex from the margin in the 
present shell; and from the O. subrugata, Minst., by the strong concentric wrinkles. It 
most resembles the Carboniferous O. xitida, Phil., but is much more depressed and 
strongly wrinkled.” 
Locality. D. perrugata is common in the Caradoc beds of Desertcreat, County 
‘lyrone; in rocks of the same age near the Chair of Kildare; at Cong, County Galway ; 
Duncannon, County Wexford, &. In Scotland it occurs at Balclatchie, Girvan Valley, 
Ayrshire. 
(?) Discina Morrisn, Dav. Pl. VII, figs. 10O—12. 
OrzsicuLa Morrisi1, Dav. Bulletin Soc. Géol. de France, 2nd ser., vol. v, p. 334, 
pl. iti, fig. 47. 
DIscina — M‘Coy. British Paleozoic Fossils, p. 190. 
Spec. Char. Almost circular, or slightly elongated oval ; free valve conoidal or limpet- 
like, and moderately elevated, the incurved vertex about one third the length from the 
posterior margin; surface smooth, marked here and there only by a few very slightly 
defined lines of growth. ‘ Lower or attached valve slightly concave at the margins and 
at the anterior half, tumid towards the opening (fissure), which is very broad, oval, half 
its length from the posterior margin, the intervening space being about one sixth the 
entire length” (M‘Coy). ‘Two specimens measured— 
Length 5, width 5 lines. 
Bah Cousens 3 
Obs. My materials in connection with this Diéscina have not been sufficient, 
and consequently I am not quite certain as to its specific value. It appears to be 
9 
