30 SUPPLEMENTARY APPENDIX. 



4. Thecidium duplicatum, Moore. 



Shell long as deep ; both valves convex, nearly equivalve ; hinge line straight ; deltidium small and 

 ill defined. Interior of dorsal valve shows a regularly granulated margin, from the centre of which, on an 

 enlarged base, rises a frontal ridge or septum, from whence is thrown off on either side a sharp ridge, 

 covered in its whole course with irregularly shaped calcareous processes, which appear long enough to pass 

 to the interior surface of the ventral valve. The lateral ridges returning to the central one describe two 

 circles. The dental valve shows three short lamellar processes under the deltidium. 



Obs. This shell is associated with Th. Bouchardii, which passes from the Upper Lias into the Inferior 

 Oolite, and with Th. triangularis. Externally it is not unlike Th. Beslongchampsii, but its internal charac- 

 ters, which are very constant, remove it from that species. 



Locality. Inferior Oolite, Dundry. 



5. Thecidium serratum, Moore. 



Shell small, inequivalve, triangular, wider than deep ; deltidium triangular, elevated, and well 

 defined ; dorsal valve small, exterior smooth : attached by a large portion of the ventral valve, which shows 

 regular striae. Internal margin of dorsal valve deeply furrowed, occupying half the ; x he valve ; 



from the margin proceed two small curved ridges, which terminate under the dental sockets. 



Obs. In most species of Thecidium the margin presents a granulated structure. This species is the 

 only one known presenting such a serrated margin, and may be at once distinguished by this character. 

 It is from the Inferior Oolite of Dundry.] 



6. Thecidium septatum, Moore. 



Shell thick, tranversely oval ; entire margin of the dorsal valve marked with fine and regular granula- 

 tions. Interior of the dorsal valve shows a septum or ridge, from which, in the centre, proceed lateral 



branches assuming the form of the letter Y> traversing the length of the shell, and occasionally dividing it 

 into three equal parts. 



Obs. The dorsal valve only of this species is known. It is more persistent in form than is usual with 



most species of Thecidium. Inferior Oolite, Dundry; rare. 



7- Spirifer oolitica, Moore. 



Shell very minute, area large, triangular : beak produced ; usually much broader than long ; having 

 nine distinct plications graduating regularly from the central one which is in relative proportion to the 

 others; without defined sinus or fold; punctuations not distinguishable: interior of the valves smooth : 

 dorsal valve having large and deep dental sockets : ventral valve having no perceptible central septum. 



Obs. The discovery of this little spirifer is of interest as it for the first time extends the range of this 

 genus into the Oolitic period. It is associated with the Brachiopods above described. 



Locality. Inferior Oolite, Dundry. 



8. Khy:nchonella triangularis, Moore. 



Shell small, thin, triangular, depressed, nearly smooth : deltidium triangular : beak produced, but 

 slightly incurved ; ventral valve slightly convex, dorsal valve proportionally concave ; thickest at the umbo, 

 nearly straight in front, from which it tapers regularly to the beak. 



Locality. Inferior Oolite, Lopen near Ilminster ; rare. 



