1867.] ETHEEIDGE XOETH DETOX. 251 



distinct species, one from the Inferior Oolite, and the other from the 

 Marlstone. It is, however, a very characteristic Neocomian shell ; and 

 some of the Lincolnshire specimens are of extraordinary size. Dwarf 

 specimens occur in the Lower Greensand of the south of England, and 

 full-sized ones in a particular zone of the Speeton clay. The species 

 is interesting as heing the largest known Pecten, either recent or 

 fossil. 



2. Ltjcina cbassa, Sow. 



The original specimen of this shell was obtained from the sand- 

 stone at Bolingbroke. That figured from the Great Oolite, by Lycett 

 and Morris, as a variety of this species is probably a distinct form ; 

 in accordance with a weU-estabHshed precedent, I would suggest 

 that it should be called L. Morrisii. 



3. Amieoxites plicomphalus. Sow. 



This is another of the Bolingbroke shells sent to Sowerby by Mr. 

 "Weir, the historian, of Horncastle. The figured specimens are both 

 somewhat obscure casts, but seem to agree with a species found in 

 the Speeton clay. A number of Oolitic forms have at different times 

 been erroneously referred to this species. 



4. Belemnites iiTNiMTJs, List., B. Listeri, Mant. et Phil., B. attenuatus, 



Sow., and B. ultimus, D'Orb. 



The whole of these forms occur together in great numbers in the 

 lower beds of the Hunstanton limestone. Prom a careful examina- 

 tion of a great number of forms, I feel convinced that they can only 

 be regarded as varieties of one species. 



Before concluding this paper, I am desirous of expressing my obliga- 

 tions to Mr. Etheridge for much advice and assistance kindly afforded 

 to me in drawing up the lists of fossils. To Prof. Huxley, also, I am 

 indebted for the examination of the specimen of Icliihyosaiwus. 



April 17, 1867. 



John Erancis Walker, Esq., B.A., E.C.S., of Sidney- SiLSsex Col- 

 lege, Cambridge, was elected a EeUow. 



The following communication was read : — 



On the Physical Strticttjee of North Devoi?^, and on the Pal^onto- 

 LOGiCAL Yaltje of the Devokean Eossils. By Eobeet Ethe- 

 ETi)GE,Esq., E.E.S., E.G.S., Palaeontologist to the Geological Survey 

 of Great Britain. 



[The publication of this paper is unavoidably deferred.] 



(Abstract.) 



The Lower, Middle, and Upper groups of sandstones and shales of 

 West Somerset and North Devon are described in this paper as oc- 

 curring in a regular and unbroken succession from north to south — 



vol. XXni. PART I. T 



