292 Dr. R. L. Sherlock — Foraminifera of Speeton Clay. 



Compared with the Red Chalk of Speeton (described by Burrows, 

 Sherborn, & Bailey), which is of the same age as the Gault, we find 

 that fifteen out of forty-three species, or 35 per cent, occur in both 

 deposits. If we compare the Speeton Clay with the Gault of 

 Folkestone (described by F. Chapman) we find that twenty-five out 

 of the forty-three species, or 58*5 per cent, occur also at Folkestone. 

 Finally, comparing the Speeton Clay with the Bargate Beds of Surrey, 

 described by Chapman, and of Lower Cretaceous age, there are 

 seventeen out of forty- three species, or 40 per cent in common. 



The fact that a higher percentage of species found in the Speeton 

 Clay occurs in the Gault of Folkestone than in the Lower Cretaceous 

 of Germany or Surrey, is to some extent, at least, due to the much 

 greater abundance of Foraminifera in the Gault. 



Little can be learnt from the Foraminifera as to the depths of the 

 sea in which the Speeton Clay was laid down. At two horizons only 

 are the species sufficiently numerous to throw any light on this 

 question. Of the thirteen species from B (base) which are still 

 living, four are at present found in water under 100 fathoms in 

 depth. In the case of Cg, of the thirteen species which are still 

 living five are at present found in water under 100 fathoms deep. 

 The remaining species in each case are found in both shallow and 

 deep seas. 



Note. — A. considerable number of the specimens are found to differ 



to a small extent from published figures of the species. These 



differences are too slight to justify varietal names, but in view of 



their presence it seems desirable to figure the species as found at 



Speeton. It is interesting to note that in Chalk forms which have 



been examined these differences are not found, showing that they 



represent real modifications of the types and are not due to imperfect 



drawings. „ 



Summary. 



1 . The Speeton Clay of Yorkshire contains abundant Foraminifera 

 in the beds named by Mr. Lamplugh B (base), Ciq, and C2 ; but the 

 specimens examined from the other subdivisions of F, E, D, and C 

 either do not contain any Foraminifera or they are present in small 

 numbers only. 



2. Two new species, Cristellaria ehapmani, PulvinuUna lamplughi, 

 and a new variety, Lagena apiculata, var. danfordi, occur and are 

 described. Forty-four species belonging to sixteen genera have 

 been found. 



3. The characteristic of the Foraminiferal fauna of the Speeton 

 Clay is the great predominance of PulvinuUna caracolla' (E,oemer) 

 over all other species. 



4. Twenty-five per cent of the species of Foraminifera occur also 

 in the Hils of North Germany, 35 per cent in the Red Chalk of 

 Speeton, 40 per cent in the Bargate Beds of Surrey, and 58-5 per cent 

 in the Gault of Folkestone. 



5. Dimorphism is clearly shown by P. caracolla (Roemer). 

 Previously it has been stated to occur among the PulvinuUna in 

 P. partschiana, d'Orb., but no case has been described. 



6. Notes are given on the microscopical characters of the sediments. 



