182 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 30, 



Upper chalk, in wliich Amorpliozoa, Bryozoa, IMonomyaria, and Bra- 

 chiopoda abound in the greatest ])roportion, while Dimyaria, Gaste- 

 ropoda, and Cephalopoda are proportionally rare : in the Upper green 

 sand, Araorphozoa, Monomyaria, and Brachiopoda are also abundant, 

 but Bryozoa are more rare, and ('ephalopoda numerous ; in which 

 two latter points that formation differs from the bed under consider- 

 ation : the strongest contrast is to the Gault and Lower green sand, 

 especially the latter, in which the Amorphozoa and Brj^ozoa are few; 

 and the prevailing families are those of the Dimyaria, Gasteropoda, 

 and Cephalopoda, in which the Farringdon deposit is particularly de- 

 ficient. Thus the first general view of its fauna would lead us to 

 place the Farringdon gravels near the top of the cretaceous series*. 



But it is necessary to examine the matter in closer detail, and to 

 compare our species with those of the several cretaceous formations 

 separately, which we will commence at the lowest. 



Lower green sand : the species common to this formation and to 

 the Farringdon gravels are the following : — 



Reptomulticava micropora. 



collis, also found in the White clialk. 



Heteropora cryptopora, also found in the Maestricht sand. 

 Proboscina marginata. 

 Terebratula tamarindus. 



oblonga, also found in the Upper green sand. 



Ostrsea macroptera, also in the Gault and Upper green sand, and perhaps 



in the Chalk. 

 Pecten Dutemplii, also in the Upper green sand. 



interstriatus, perhaps identical with T. Dutemplii. 



Serpula quinque-angulata. 

 Salenia punctata, of Atherfield. 

 Goniopygus peltatus, of Switzerland. 

 Diadema dubimn, do. 



The number of species hitherto known only in the Lower green 

 sand is so small compared \\\t\\ the total number found at Farringdon, 

 as to send us higher up in the series for the synchronism sought. 



Gault : this formation offers fewer points of comparison than even 

 the preceding ; the only Farringdon species also known in the Gault 

 being the following : — 



Multicrescis mammillata. 

 Rhynconella antidichotoma ? 

 Ostraja macroptera, also in Ujjper green sand. 

 . Pecten Raulinianus. 

 Serpula plexus, also in Upper green sand, and Upper and Lower chalk. 



The shortness of this list, and the absence of all the characteristic 

 gault shells, remove the deposit from any connection with the Gault. 



Ujjper green sand : we find here, for the first time, materials for a 

 serious comparison with the Farringdon fossils ; and this comparison 

 is strengthened if we add the Tonrtia of Belgivun to the Upper green 

 sand, as has been done by INL d'Archiac, whose excellent memoir on 



* Compare the list of organic remains of Farringdon with the " Tableau de la 

 Faune Cretacee d'Aiigletcrre." d'Archiac, llistoire, vol. iv. p. 109. 



