PRESTWICH CRAG-BEDS OF STTFEOLK AlfD KORFOLK. 133 



had been found, but nothing else. But here again, as with the Eed 

 Crag, the cause of their non-discovery appears to have been that they 

 are confined almost entirely to the basement-bed of both deposits, and 

 this bed, in the Coralline Crag, as well as in the Red Crag, proves to 

 consist chiefly of water- worn fragments and pebbles derived from 

 older deposits. It was only at one small pit, and there for a short 

 time, that the bed of phosphatic nodules at the base of the Coralline 

 Crag was worked ; and yet there were there found as many, or more, 

 specimens than are usually found in Red- Crag workings of the same 

 extent. The following species have been found : — Mastodon ar^ 

 vernensis, Rhinoceros (Schleiermacheri ?), Cerviis, BelemnozipMus, 

 Balcena. 



The large teeth of Carcharvdon, the skull-bones of Belemnoziphius 

 and the flat Cetacean bones are all drilled superficially by some 

 boring animal. This must, in all probability, have been done be- 

 fore the bones were fossilized ; and as the holes present mere seg- 

 ments of their original forms, either they may have been rolled 

 and worn so as to reduce the thickness of the bone and so remove 

 a portion of the drilled surface, as has been suggested, or else the 

 bones may have been originally imbedded in some clays or marls 

 through which boring shells may have drilled until, coming into con- 

 tact with the harder bone, they merely impinged on its surface, which 

 they failed to penetrate. Neither explanation, however, is satis- 

 factory. In the one case, the bones have generally lost little or 

 nothing of their substance, while the difiiculty on the latter suppo- 

 sition is that many of these bones are drilled on all sides ; one of the 

 skulls of the BeleynnoztpTiius, for example, shows traces of these 

 holes on all its four surfaces, whereas, if the bone had been im- 

 bedded in clay or marl, we should have looked for perforations in 

 one surface only. 



The condition, in fact, of the bones at the base of this Crag is 

 precisely of the same character as that of those at the base of the Red 

 Crag. In both they are worn and mineralized. At the same time 

 I think it not improbable that the Mastodon and the Rhinoceros 

 may have lived at the Coralline- Crag period — though the general 

 absence* of all bones other than teeth, and the circumstance that 

 the materials of the bed in which they occurred is so largely deri- 

 vative, throw doubt on the whole collection generally. The Whale 

 certainly lived at that period. The condition of many of the ver- 

 tebrae, their distribution at various levels, and the occurrence, in 

 one case, of seven vertebrae in connexion, show that this animal 

 lived in the CoralHne-Crag sea, as did probably some of the other 

 Cetaceans. 



From the preceding particulars of the fauna of the Coralline Crag, 

 it would seem that the differences in the proportions of recent to 

 extinct species in the different classes is so great that I do not see 

 how the results are at present to be reconciled. As with the Mol- 

 lusca, however, I think it extremely probable that the other groups 

 wiU, after we know more of their distribution in the greater depths 

 of the Atlantic, be found to require considerable revision. In the 



