400 



Messrs. Carpenter and Brady on 



[Apr. 22, 



curves show the deviations of the semiannual means from it. In both 

 figures the curves between twelve and fifteen hours and fifteen and eighteen 

 hours are interpolated. 



Figures 2 and 4 are copied from General Sabine's St. Helena Observa- 

 tions, vol. ii., and show the similarity between the movements of the mag- 

 net at Ascension and St. Helena. 



The Tables annexed to this Paper are preserved for reference in the 

 Archives. 



April 22, 1869. 

 JOSEPH PRESTWICH, Esq., Vice-President, in the Chair. 



Alphonse DeCandolle, of Geneva, Charles Eugene Delaunay, of Paris, 

 and Louis Pasteur, of Paris, were proposed for election as Foreign Members, 

 and notice was given from the Chair that these gentlemen would be 

 ballotted for at the next Meeting. 



The following communications were read : — 



I. "Description of Parkeria and Loftusia, two gigantic Types of 

 Arenaceous Foraminifera. " By Dr. Carpenter, V.P.R.S., and 

 H. B. Brady, F.L.S. Received March 18, 1869. 



(Abstract.) 



The Authors of this Memoir commence by referring to the separation of 

 the series of Arenaceous Foraminifera from the Imperforate or Porcel- 

 lanous, and from the Tubular or Vitreous, first distinctly propounded in 

 Dr. Carpenter's 'Introduction to the Study of the Foraminifera' (1862), 

 on the basis of the special researches of Messrs. Parker and Rupert Jones ; 

 who had pointed out that whilst there are several genera in some forms of 

 which a cementation of sand-grains into the substance of the calcareous 

 shell is a common occurrence, there are certain genera in which a "test" 

 formed entirely of an aggregation of sand-grains takes the place of a cal- 

 careous shell ; and that these genera constitute a distinct Family, to which 

 important additions might probably be made by further research. 



The propriety of this separation of the Arenacea from the calcareous- 

 shelled Foraminifera has been fully recognized by Prof. Reuss, the highest 

 Continental authority upon the group • who had come to accept the prin- 

 ciple laid down in Dr. Carpenter's successive Memoirs (Phil. Trans. 1856- 

 1860), that the texture of the shell is a character of fundamental im- 

 portance in the classification of this group, the plan of growth (taken by 

 M. d'Orbigny as his primary character) being of very subordinate value ; 

 and who had, on this basis, independently worked out a Systematic Ar- 

 rangement of the entire group, which presents a most remarkable cor- 

 respondence with that propounded by Dr. Carpenter and his coadjutors. 

 And their anticipation of important additions to the Arenaceous series has 



