162 BRITISH CARBONIFEROUS BRACHIOPODA. 



valves. In some specimens these ridges are very regular and uninterruptedly continuous, 

 but in the larger number of individuals some of them are here and there interrupted in 

 their course and absorbed, while two at other times unite during their passage along 

 the middle. The radiating thread-like striae bear much resemblance to those of P. Cora, 

 and increase in number here and there bv interstriation. 



In England, P. undatus occurs in the lower scar limestone of Settle, in York- 

 shire, in the lower Carboniferous limestone of Lowick, Northumberland, middle limestone 

 of Poolwash, Isle of Man, and upper Carboniferous limestone of Derbyshire. In Scotland, 

 it occurs in limestone at Gare and Headsmuir, at about 240 fathoms below the 

 horizon of the " Ell Coal." In Stirlingshire, in the Campsie main limestone, and at 

 Castlecarry, in Dumbartonshire. In Ireland, at Tullynagaigy, Ferruanaugh, and at Little 

 Island, near Cork. 



On the Continent, it occurs in the limestone of Vise, in Belgium, and at D'Unja, near 

 Kosimof, as well as at Nikoulin and Karova, in Russia. M. de Koninck mentions also 

 that a specimen is preserved in the Museum of Paris, found in Tasmania. 



Productus Wrightii, Bav. PI. XXXIII, figs. C, 7. 



Spec. Char. Shell small, transversely oval ; hinge-line rather less than the width of 

 the shell. Ventral valve convex and regularly vaulted ; beak and auriculate expansions 

 small. Surface covered with numerous smooth, regular or irregularly interrupted, undulating, 

 concentric folds or wrinkles, from which, at short intervals, project scattered spines ; the 

 margin of the valve is, moreover, bent up at right angles, forming a wide, flattened, but 

 ribbed boarder or frill round the shell. Dorsal valve and interior unknown. The largest 

 specimen hitherto discovered measures — length 3^, width 5 lines, of which the bent-up 

 margin is from 1 to \\ line in width. 



Obs. Of this interesting little species two examples were discovered by Mr. J. Wright. 

 in the Carboniferous limestone of Middleton, near Cork, in Ireland, and have been considered 

 by Prof, de Koninck, as well as by myself, a new species (?) The concentric folds or wrinkles 

 resemble much those of P. undatm in their terrace-like arrangement, but are dis- 

 tinguished by the total absence of those longitudinal, thread-like striae so beautifully 

 disposed in Defrance's species ; the wide fringe or frill which surrounds the shell is also 

 peculiar. 



The species is named after Mr. Joseph Wright, to whom the author of this monograph 

 is indebted for much valuable material and information relative to the species from 

 the neighbourhood of Cork, in Ireland. 



