570 



J. E. BLAKE ON THE TJPPEK 



the lithographic limestone mass, since the fossiliferous sponge-bed 

 is characterized by Ammonites canalieulatus and other species be- 

 longing to a lower horizon, though the recorded presence (60) of 

 A. marantianus shows that we are there not far off the top. In the 

 Lower Charente, the locality Marans has beds below any thing seen 

 at La Rochelle. In the Sarthe the description of M. Hebert (21) 

 would lead us to place his "Middle Oxfordian" as Oxford Grit, which 

 here returns to its usual character, and his " Upper Oxfordian," 

 which is here marly, as Oxford Oolite. On the coast of Calvados 

 we find in the Trouville Oolites, seen in true succession in the cliff 

 of Auberville, a good palaeontological representative of the Neuvizy 

 ironstone ; and below comes the Oxford Grit, with an equally cha- 

 racteristic fauna. The lower of these two beds is considered by 

 Hebert (28) to be Middle Oxfordian, and therefore to correspond to 

 the JNTeuvizy ironstone, and the rest to be Upper Oxfordian ; but the 

 Neuvizy ironstone is certainly more allied pala3ontologically to the 

 upper beds, and the grits associate themselves with these more 

 completely than with the beds below. 



The series here, as has been seen, corresponds exactly with that at 

 Weymouth — the]N"otheGrits,theJN"otheClays,theBencliffGrits,andthe 

 Osmington Oolites all following regularly. The last named, therefore, 

 are to be specialty paralleled with the Neuvizy ironstone, with which 

 they have 29 per cent, of their fossils in common, and must be called 

 Oxford Oolite, and the grits below, Oxford Grit. Whether the Trigonia- 

 beds of Weymouth are to be also included is a more difficult matter, 

 to be discussed hereafter ; but we must certainly place on the same 

 horizon the pisolites of North Dorset and the oolite of Highworth, 

 which has 57 per cent, of its fossils common to Neuvizy, and perhaps 

 also the road-stones of Faringdon. Unfortunately at Oxford the 

 "Oxford" Oolite is not well represented, except near Marcham. At 

 Upware the limestones of the north pit belong here. The great 

 development in Yorkshire gives us for the Oxford Grit the whole 

 mass up to and including the Passage-beds, and for the Oxford 

 Oolite as far up as the Trigonia-beds of Pickering, the latter having 

 55 per cent, in common with Jfeuvizy. In fact, the greater part of 

 the limestones which underlie the Coral Rag proper belong to this 

 portion. 



Our circle is finally completed in the Boulonnais, where the 

 limestone of Houllefort, in the midst of clays, offers us the only 

 representative of this part of the series, though to what exact part 

 it may be considered to correspond may be doubtful. The excep- 

 tional presence in it, however, of Cidaris fiorigemma indicates a high 

 position. 



We have next to discuss the Corallian series. De Loriol (50, 

 56) and Tombeck would have us abolish the term altogether ; 

 and Oppel (27) practically does so by including his " zone of Cidaris 

 florigemma " in the Oxfordian. The argument against its use is that 

 coral-growth is only an accident which may happen at any time, 

 and that there is much of the so-called Corallian which has no corals 

 in it. These statements are doubtless true, and yet, to one who has 



