Yol. 56.] EARLIEST-KNOWN FORAMINIFERA. 263 



by associated Dikelloceplialus, occurred in Siberia and was crowded 

 with various vitreo-perforate foraminifera. 



Dr. G. J. Hinde enquired whether any of the characteristic zonal 

 trilobites mentioned had been found in the same detached rock- 

 fragments with the foraminifera, so that their age was incontestably 

 fixed ; and whether the Author was satisfied with respect to the 

 nature of the presumed foraminifera from the pre-Cambrian rocks of 

 Britanny. 



Prof. Groom, in reply to Dr. Hinde, stated that the characteristic 

 trilobites of the SjphceropTitJtalmus- zone had not been detected in the 

 limestone, although they occurred in the associated shales a few 

 yards away. The foraminiferal rock evidently occurred in the 

 heart of the "zone. 



The Author, also in reply to Dr. Hinde, said that the figures 

 given by Cayeux of foraminifera from the pre-Cambrian rocks of 

 Britanny did not show the structure of the test. Although they 

 bore a general resemblance in outline to some genera with a finely 

 arenaceous shell-wall, as Hormosina., yet they must be regarded as 

 of doubtful organic origin. 



