34 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [Apr. 14, 



Gastrochsena dubia. Sphenotrochus intermedius. 



Teredo Norvegica. Cryptangia Woodii. 



Balanophyllia calyculus. 

 Terebratula grandis. Fascicularia. 



Theonoa. 

 Balanus coneavus. Cellepora. 

 crenatus. Esehara monilifera. 



Alcyonidium circumvestiens. 



In the Table appended to these remarks (see p. 43), no notice 

 whatever is taken of these doubtful fossils, as it is possible that they, 

 or at least some of them, may have lived on to the Eed Crag Period 

 from that of the Lower or Coralline Crag ; still, however, there are 

 some few extraneous fossils of the alien character of which there is 

 no doubt ; but, the species not having yet been obtained in any other 

 deposit, we are unable to refer them decidedly to a particular period. 

 There is, however, an unmistakeable character about them by which 

 we may, I think, with every probability not only infer their derivative 

 nature, but assign to them the formation to which they originally 

 belonged. I would especially mention the casts of two species of 

 Pulmonifera : one a large elevated HelicCy and the other a species of 

 dextral Bulimus, differing from anything that has hitherto been 

 described as from the Older Tertiaries of this or any other countrj^ 

 known to me; but I have very little doubt they are casts of shells 

 from a freshwater deposit, probably belonging to, or synchronous 

 with, one of the Older divisions of the Eocene Formation. 



The air-breathing animals of all kinds found in this marine de- 

 posit, I have considered as not entitled to be enumerated with the 

 real inhabitants of the Red Crag Sea, although it is probable that 

 Helix rysa and Planorhis marginata may truly belong to the age of 

 the bed in which they are found. The terrestrial Yertebrates are 

 certainly intruders into the Crag, to whatever period they may be 

 assigned ; and the opinions of the present day respecting the Age to 

 which they belonged are in a most unsatisfactory state, our ablest 

 Palaeontologists being at variance in the assignment of the species. 

 Prof. Owen* considers many of them as having been derived from 

 the Miocene or Middle Tertiaries, while Dr. Falconer f has more 

 recently identified them with species belonging to the Newer Ter- 

 tiary or Pliocene Period ; and, in this state of uncertainty, I have 

 purposely omitted their specific names from my Catalogue, which is 

 entirely restricted to the Eed Crag. 



Mr. Charlesworth, it is well known, orginally separated the Crag 

 deposits into three chronological groups, but the propriety of these 

 divisions has lately been called in question, and it is asserted they 

 all belong to one period as indicated by the Mammalian Remains 

 that have been found in them. 



Whatever may be considered necessary to mark what is called a 

 Geological Period, whether it be an entire alteration of the fauna of 

 a preceding specified portion of the world's existence, or the change 



* Quart. Journ. Geol. Soc. vol. xii. p. 217, &c. 

 t Quart. Journ. Geol. Soc. vol. xiii. p. 350, &c. 



