132 BRITISH CARBONIFEROUS BRACHIOPODA. 



Ortiiis Keyserlingiana, De Koninck. PI. XXVIII, fig. 14. 



Orthis Keyseki.ingiana, Be Koninck. Description des Animaux Fossiles qui se trou- 



vent dans le Terrain Carbonifere de Belgique. 

 p. 230, pi. xiii, fig. 12, 1843. 



Spec. Char. Shell transversely oval or sub-quadrate, with rounded angles ; ventral valve 

 convex, and much deeper than the dorsal one, with a deep longitudinal median sinus or 

 groove, which extends from the extremity of the incurved umbonal beak to the front, this 

 valve being likewise the longest and largest, on account of the umbonal beak being more 

 elevated than the level of the beak and area of the dorsal one ; area narrow. Dorsal 

 valve straight, flattened, and sometimes slightly concave from the extremity of the beak to 

 the front, the lateral portions sloping gently on either side ; area triangular, flattened, and 

 bent backwards ; beak small, angular, slightly convex, and on a level with the area; fissure 

 triangular, open ; margin moderately flexuous. Exteriorly, each valve is covered with 

 numerous thread-like, rounded, radiating stria v , which increase in number by the means 

 of numerous interstriations and bifurcations from the extremity of the beak to the front ; 

 the striae at intervals augmenting in thickness as well as projection, and giving rise to 

 small thread-like spines (broken close to the surface in the generality of specimens). 

 Numerous concentric lines of growth are also observable on the valves, which are likewise- 

 perforated by minute tubuli. Interior unknown. 



Two specimens have measured — 



Length 11, width 12|, depth 6| lines. 

 „ 8, „ 10, „ G 



06s. This interesting and well-marked species was first brought to my notice as 

 British by Professor de Koninck, who had received a specimen from England, but without 

 locality ; and it was only after some research that I learnt that Mr. Burrow had found 

 several examples in the Carboniferous limestone of Settle, in Yorkshire, this being also the 

 only British locality, with which I am at present acquainted, wherein the shell has been 

 discovered. 0. Keyserlingiana cannot be confounded with 0. resupinata, on account of its 

 peculiar and different shape, although the striation is very similar in both. In Belgium, 

 it has been found occasionally at Vise. 



Orthis Michelini, L. Eveille. Plate XXX, figs. 6 — 12. 



Terebratula Micuelini, VEveillv. Mem. de la Soc. Gee-1. de Frar/ce, vol. ii, p. .'39. 



pi. ii, figs. 14—17, 1835. 

 Spirifera filiaria, Phillips. Geol. of Yorks., vol. ii, pi. xi, fig. 3, 1836. 



