168 



INFERIOR OOLITE AMMONITES. 



Beds. 



Yorkshire. 



Northampton. 



Cotteswolds, 



Haresfield-Wotton 



District. 



Dorset-Somerset 



District 



(south of MeiMiips). 



Opalinum. 



Absent? 



Northampton 

 Sands. 



Sandy ferruginous 

 Limestone. 



Inferior Oolite 

 Limestone. 





Moorei. 







Yeovil 



Dumortieria. 



Yellow Sands, 



Grey Sands, 



below Dogger. 





Cephalopoda- 



Sands. 



Dispansum. 



The 



Absent. 



bed. 



" Upper 



Striatulum. 



Striatulus- 







Lias 



Variabilis. 



shales. 





Cotteswold 



Clay." 



Commune. 



The Alum-shale. 



"Upper Liaa Clay" 



Sands. 





"Upper Lias Clay" 



The Northampton Sands contain representative species of the OpaZmwrn-beds ; 

 but all the evidence obtainable seems to point to the absence of beds from Moorei 

 to Variabilis inclusive. I have seen no Ammonites of any of those horizons, nor 

 have any of the species been quoted. 



Erom Dundry, which is not included in any of the above districts, Mr. B. 

 Wilson, F.G.S., has sent me specimens of Gramm. striatulum and Gramm. aalense, 

 indicating the presence of the Striatidum- and Moorei-heds. Possibly more of the 

 horizons may be present, but the deposit is very thin, and is only occasionally, 

 and very poorly, exposed. 



From Cranmore, Somerset, which I have not really included in the above districts, 

 Mr. Hudleston sent me Gramm. fallaciosum indicative of the Disj)a7isnm-heds. 



It may be advantageous to say a few words concerning some of the foreign 

 works which deal almost exclusively with the fauna of the Jureiise and Opalinum 

 zones, and consequently with the genus Grammoceras. Of course I have no need 

 to mention what may be regarded as the standard works of d'Orbigny, Quenstedt, 

 &c., but will notice the following : 



Dumortier, ' Etudes Paleontologiques sur les Depots Jurassiques du Bassin du 

 Rhone.' Quatiemc partie, 'Lias Superieur,' Paris, 1874. This admirable work con- 

 tains excellent figures of many species of Grammoceras, besides many other 



