THE PLIOCENE BEDS OF ST. ERTH. 



205 



are some minute stellate spicules of calcareous composition which, 

 with the kind assistance of Mr. Eidley, of the British Museum of 

 Natural History, we determined to belong to an order of the In- 

 vertebrata which has never before been found in a fossil state, viz. 

 the Tunicata ; but in order to make quite sure of its affinities, we 

 submitted specimens to the judgment of Professor W. A. Herdman, 

 of University College, Liverpool, who confirmed our determination, 

 and pronounces it closely allied to Leptoclinum tenue, a species 

 to be mentioned in the second part of his report on the ' Challenger ' 

 Tunicates, which is now in the press. 



The Poraminifera and Ostracoda are present in large numbers ; of 

 th-e former Mr. P. J. Millet, of Marazion, found about one hundred 

 and twenty species and varieties ; and the Ostracoda, which are in 

 the hands of Messrs. Brady and Robertson, seem individually quite 

 as numerous, every part of the clay from bed No. 4 yielding multi- 

 tudes of examples of both these groups. 



With regard to the Mollusca, which, as in nearly all other deposits, 

 present the best means of determination respecting age, climate, 

 and other conditions, much, in our opinion, remains to be learned ; 

 but enough is known to enable us, with some degree of certainty, to 

 confirm the view expressed by the late Mr. Wood as to the date of 

 the Blue Clay ; we think there is little doubt of its being of Pliocene 

 age and contemporary with the middle or lower portion of the Red 

 Crag. Several remarkable shells, which have always been regarded 

 as characteristic of that deposit, occur here, such as Littorina sub- 

 aperta^ Conovulus pyramidalis, Nassa granuJata, and Columhella 

 sulcata ; the first two occur only in the Red Crag and one of the 

 Belgian upper Crags, the last not earlier than the Coralline Crag, 

 where it is very rare, and certainly not the same form as the single 

 St. Erth shell, which is large, and resembles the coarser varieties of 

 the Middle Red Crag. The large numbers of Nassa serrata or 

 reticosa (these species are undistinguishable), Turritella incrassata, 

 and Naiica millepu aetata, which similarly occur in plenty in both 

 deposits, tend to the same conclusion as to the identity in time of 

 the St. Erth deposits and the Red Crag. At the same time it must 

 not be overlooked that a small number of important and prominent 

 species occur at St. Erth which have no representatives in the Crags of 

 Suffolk, and are entirely of a southern character, such as Fasus cor- 

 neus or lignarius, Nassa miitahilis, Gardium papillosum, and Cardita 

 aculeata. Three of these species have never been found in Great 

 Britain, either fossil or recent, and, excepting in the Italian Pliocenes 

 and Prench Miocenes, have never before been noticed north of the 

 Mediterranean and. Cadiz ; and it will be observed, on reference to 

 the synoptical list at the end of this paper that, with the exception 

 of three species of small size, nearly the whole of the shells which 

 have a living-range into the seas of Norway, also extend in a 

 southerly direction into the Mediterranean. 



It may be as well to call attention to the large size of these 

 St. Erth examples of peculiarly Mediterranean Mollusca, such as 

 Nassa mutabilis, Turritella incrassata, &c. ; these far exceed any 

 examples in the seas or formations of Southern Europe, and although 



