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SUPPLEMENT TO THE BRITISH 



central one, and towards the front are short rounded ribs with interspaces of about equal 

 breadth. In the interior of the dorsal valve, at a short distance from the margin, a raised 

 granular ridge surrounds the shell, and from which arises a lanceolate septum which 

 extends to nearly two thirds of the length of the shell. A supra-membraneal granular 

 disk forms likewise two circular platforms on each side of the median septum. The 

 raised margin of the shell is also granulated. This species was well described by Mr. 

 Moore who states that the interior of the ventral valve is not unlike that of Th. serration, 

 but that it wants the elevated front of that species, and that it may also be distinguished 

 by its more oval shape and less produced beak. He adds likewise that when the supra- 

 membraneal disk is wanting, the dorsal valve shows two small oblong elevations on each 

 side of the septum. The shell is very small, not much more than half a line in length 

 and width, and is said by Mr. C. Moore to occur in the Inferior Oolite of Dundry. 



60. Thecidium granulosum, Moore. Sup., PI. XII, figs. 1 — 5. 



Thecideum granulosum, Moore. Proceedings of the Somersetshire Archaeological and 



Nat. Hist. Soc, vol. for 1854, p. 117, pi. ii, figs. 

 1—6. 



" Shell thick, longitudinally oval, area triangular, concave ; deltidium flattened ; hinge- 

 line straight, outer side of dorsal valve convex, having lines of growth and short striae 

 towards the frontal margin, ventral valve having a sinus in the centre. Interior of 

 ventral valve has a central ridge through its greater length, on each side of which are 

 muscular impressions. The interior of the dorsal valve has a flattened thickly granulated 

 margin, within which a raised ridge, formed of larger single granulations, united in the 

 centre by a septum occupying about one half the length of the shell, sometimes smooth, 

 at others covered with granulations, and joined over the visceral cavity by a bridge, the 

 equivalent of the crural processes of Terebratula ; within this ridge occurs a small raised ridge, 

 answering to the loop in other Brachiopoda to which were attached the brachial membrane 

 and oral arms, within which, and occupying the larger portion of the cavity of the shell, 

 occurs a calcified supra-membraneal disk, divided by the septum into two lobes of brain - 

 shaped convolutions, the free portion of which extends over the visceral cavity. This 

 species presents considerable variety in most cases depending upon the completeness of the 

 supra-membraneal disk." 



I have reproduced Mr. Moore's description as it conveys all we know 7 upon the 

 subject. The shell attains to nearly two lines in length and quite that in breadth. It 

 was found by Mr. Moore in the Inferior Oolite at Dundry. 



