252 NOTES ON THE BEITISH JUEASSIC BKACHIOPODA. 



and rounded, encroaching on both valves, or triangular ; 

 valves depressed and convex ; dorsal valve usually most so ; 

 external surface rugose, showing slight tendency to stria tion, 

 at others having concentric lines of growth, which are more 

 defined on the ventral valve ; valves articulate. Inteiior 

 of dorsal valve granulated or smooth, showing flattened, 

 granulated or smooth margin, surrounded by an elevated 

 ridge which, commencing under the dorsal sockets, passes 

 to the front of the shell, where it is partly obliterated, and 

 is then united by a central septum." 



Moore adds that, " Zellania has affinities with Thecidea, in 

 having internal ridges and a central septum ; and will 

 consequently unite the Terebratulidse with the Thecideidse. 

 The probability of the existence of a loop such as that 

 possessed by Megathyris (Argiope), has been suggested by 

 Mr. Davidson ; but although I have, in several instances, 

 made dissections for the discovery of this loop, its existence 

 cannot be satisfactorily established " (15, p. 107). 



Zellania is apparently confined to the Jurassic rocks, where 

 it is represented by six species, as follows : — 



Z. davidsoni, Moore, type obtained from the Inferior 

 Oolite of Diindry, where the species is stated by Moore to 

 be not uncommon, 



Z. globata, Moore, from the Fuller's Earth of Bath ; Great 

 Oolite of Hampton Cliff ; and the Coral-rag of Lyneham, 

 Wilts. 



Z. lahoucherei, Moore, type from the Inferior Oolite of 

 Dundry, and at present in the Bath Museum. This species 

 and Z. davidsonl is also recorded from the Lower Lias of 

 Brocastle. 



Z. liasiana, Moore, Upper Lias, Ilminster. 



Z. ooUtica, Moore, type from the Inferior Oolite of 

 Dundry. 



