168 PAPERS, ETC. 



minute, is very persistent in its form, I have ventured to 

 give it the above specific designatlon. 



Thecideum trianguläre, D'Orbigny. 



This species has hitherto been noticed only in the Middle 

 and Upper Lias, and the Inferior Oollte. I have novv 

 obtained it from the Lower Lias of Keynsham, which is 

 the oldest formation in which it has yet been found. It 

 then passes through the beds above mentioned, and is very 

 common — attached to Lima, Ostrea, and other shells — in 

 the Fuller's Earth of Combehay, near Bath. It occurs 

 also in the coralline bed of Hampton Cllffs, and again in 

 the still higher zone of the Coral Rag of Lyneham. No 

 other species of Brachiopod has yet been known to have 

 attained so long a ränge as is indicated by the above facts. 

 Its uninterrupted passage through so many forraations 

 points out the absence of any considerable climatal or 

 other changes during the deposition of the beds in which 

 it is found. 



I have evidence of the presence of several other species 

 in the Inferior Oolite of Dundry, one very nearly approach- 

 ing the T. Dcslovgchampsii, Dav. ; but as only separate 

 valves have been found, it will be unsafe at present to say 

 more respecting them. 



CEANLi, Eetzius. 



Crania canalis, Moore. 



PI. IL, figs. 8-10. 



Shell subquadrate, usually flattened, at other tinies more 



or less conical. The outer surface of the young shell 



exhibits a few coarse strife, which continue to the margin 



of the valve. In the adult these becorae much more 



numerous, many of them passing as narrow spines, some 



