38 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 14, 



assist oiir calculations, the length of these extinct animals to which 

 the large teeth belonged may probably be found not to have ex- 

 ceeded in length that of sharks existing in the seas of the present 

 day, namely 60 feet. 



Besides the fish- teeth, which are found in great abundance in the 

 Eed Crag, there are " coprolitic " casts of the animals themselves, 

 indicating their derivation to be from a bed of the Older Tertiary 

 Period. These specimens are generally in a fragmentary, often in 

 a rolled and mutilated, condition. They bear a strong resemblance 

 to, and indeed in a few instances the Crag specimens can be iden- 

 tified with, the fossil fishes of the Isle of Sheppey. 



A few specimens only of Cephalopoda have come under my notice. 

 These consist of, first, Belemnites, probably belonging to two species, 

 and derived from the upper part of the chalk formation. They are 

 silicified, having the surface ornamented with a peculiar arrange- 

 ment of elevated concentric ridges, or points, somewhat irregular 

 and imdulating. I have separated these into two species, although 

 the specimens are not in the most satisfactory condition for such a 

 purpose ; but one or two show a great eccentricity in the alveolus ; 

 and I have depended upon that character alone for the distinctions. 

 Secondly, nodules containing impressions of Ammonites. These 

 appear to consist of calcareous clay, probably of the age of the lias. 

 Thirdly, a few nearly perfect casts of Nautilus have been obtained ; 

 and segments, or casts of the compartments, are occasionally met 

 with. Those which I have seen were not in a condition to justify 

 the assigning to them more than a generic character. As, how- 

 ever, they are casts formed of the material which resembles the 

 phosphatic clay of the Older Tertiaries, they are on that account pre- 

 sumed to have been derived from the London Clay. The evidence 

 afforded by the derivative Mollusca, or rather I should say the Gas- 

 teropoda and Bivalves, point in the same direction as the greater 

 part of the Fish-remains, namely, to the London Clay; but the 

 sJiells of the Older Tertiaries are rarely found, as might be ex- 

 pected; and the casts, which are seldom in good condition, will 

 only occasionally afford a specific character, although their general 

 form will admit of no mistake. Those which give a fair determina- 

 tion indicate their age to be that of the older portion of the Eocene 

 deposits, with, however, the exception of one shell, Ostrea flahel- 

 lula, which belongs to the upper division ; but even this is found in 

 the Bracklesham beds, and I have seen in Mr. F. Edwards's Col- 

 lection a shell much resembling it, which came from Clarendon. 



Many Crustacean remains (five, perhaps six, species) found in the 

 Eed Crag can be traced to the Eocene deposits. Some of these are 

 imbedded in the phosphatic clay, and others are simply casts formed 

 of that material. They are not only identical with London Clay 

 species, but there is oftentimes so strong a resemblance between 

 the Crag specimens and those from Sheppey, that, with the excep- 

 tion that the former are tinged with the ochreous colour of the Eed 

 Crag and are more rubbed, they could scarcely be distinguished the 

 one from the other. I believe all these derivative Crag specimens 



