136 PKOCEEDINGS OP THE GEOLOGICAL SOCIETY, 



forms wHch are now confined chiefly to the Scandinavian or 

 Arctic provinces. These appear from the commencement of the 

 Crag period. Of the exact ratio in which these forms may have 

 increased during that period we are yet ignorant. 



The relation which the Coralline Crag bears to the Crags of Ant- 

 werp has been the subject of much inquiry. It was first treated in 

 a systematic manner by Sir Charles Lyell, and his conclusions still 

 generally hold good. The corrected lists and more exact divisions of 

 the several members of the Antwerp Crag, recently given by Prof. G. 

 Dewalque, have, however, rendered some modification necessary. 



Taking the Belgian beds in descending order, the relation which their 

 moUuscan remains show to those of the Coralline Crag; is as under : — 



No. of species of 



No. common to the 



Proportion of 



Mollusea in the 



Antwerp beds and 



Coralline-Crag 



Antwerp beds. 



the Coralline Crag. 



species. 



Scaldisien.|^^S^^>"^^^- }^7 ... 

 1 Sables gris ... 187 



135 

 133 



. 69 per cent. 

 . 71 



Diestien Sables noir s . . . 228 



98 



. 43 „ 



This question will be treated more fully in the next part of this 

 paper, in connexion with the E,ed Crag, 



"With the Pliocene beds of Monte Mario the Coralline Crag has 147 

 species in common. 



P.S. Owing to the great additions made to the number of known 

 species, and the recognition amongst them of so many Crag species 

 in the recent deep-sea dredgings, the CouncU of the Society have 

 kindly allowed me to bring the lists of fossils up to the present date 

 (April 1871), 



List of the Mollusea found in the Coralline Crag. 



This List (alphabetically arranged) is compiled from the Monograph 

 of Mr. SearlesWood, with the addition of Mr. Davidson's Brachiopods, 

 whose references and names of species are given in columns I. and II. 

 Mr. JeflPreys has, with the assistance of Mr. Bell, made some addi- 

 tions to the list of species ; these have the letter J prefixed to them 

 in column I. The names to which a f is prefixed denote species 

 which Mr. Jeifreys identifies with those now living, in addition to 

 all the species which had been already recognized by Mr. Wood to be 

 living *, Every form regarded by Mr, Jefireys as a variety ranges 

 through all the columns in italics. 



Column III. comprises the names adopted by Mr. Jeffreys, except 

 those to which a ^ is prefixed, which he regards as synonyms, or 

 names of later date, but desirable to notice. In this column also 

 are added other names adopted by M. Nyst for the Belgian Crags ; 

 the last are within brackets. 



Columns IV. and Y. indicate the zones of depth or bathymetrical 

 range, and the geographical distribution, both of which have been 

 furnished by Mr. Jeff'rejs. 



* A very few species, to the names of which a t is prefixed, are not the spe- 

 cies to which Mr. Wood referred the Crag fossils, although the latter are living. 

 These are Bulla Lajonkairecma, Eulima subulata, Odostomia truncatula, Eissoa 

 costulata, and Tro'p'hon gracile. — J. Gr. J. 



