]Mr. J. G. Jeffreys on British Foraminifera. 75 



Thus, to give an example, 

 P„=P(11,2) + P(11,3) + P(11.4) + P(11,5) 



=I(11,2) + I(11,3)+I(11,4) + (I(11,5) = 0) 



+ P(11,2) + P(11.4) 



+R(n>2) + R(ll,3) + R(ll,4)+R(ll,5). 

 I(U, 2) = I-(9, 2) . II-(9, 2, 0) + I(9, 2) . 11(9, 2, 0) ; 

 I(11,3) = I(8,2).II(8, 2,1) + R(8,2).IR(8,2,1) + I(8,3).I(8,3,0); 

 1(1 1, 4)=P(7, 2) . IP(7, 2, 2) +R(7, 2) , IR(7, 2. 2) 



+ R^(7,3).IRX7,3, 1); 

 P(ll, 2)=P(9, 2) . PP(9, 2. 0) ; 

 P(ll, 4)=P(7, 2) . PP(7, 2, 2) ; 

 R(ll, 2)=R(9, 2) . RR(9, 2. 0) ; 

 R(ll, 3) = R(8, 2) . RR(8, 2, 1) ; 



R(ll, 4) = R(7, 2) . R(7, 2, 2) + RX7, 3) . RRX7, 3, 1) ; 

 R(ll, 5)=R(6, 2) . RR(6, 2, 3). 



The result is 



Pu = Iii + Iii + Rn = 61+7 + 12 = 80. 



" Notes on British Foraminifera." By J. Gwyn Jeffreys, Esq., 

 F.R.S. 



Having, during a great many years, directed my attention to the 

 recent Foraminifera which inhabit our own shores, I venture to offer 

 a few observations on this curious group, as Dr. Carpenter, who has 

 favoured the Society with an interesting and valuable memoir on 

 the subject, seems not to have had many opportunities of studying 

 the animals in the recent state. 



Rather more than twenty years ago I communicated to the Lin- 

 naean Society a paper on the subject, containing a diagnosis and 

 figures of all the species. This paper was read and ordered to be 

 printed in the Transactions of that Society ;. but it was withdrawn 

 by me before publication, in consequence of my being dissatisfied 

 with D'Orbigny's theory (which I had erroneously adopted), that 

 the animals belonged to the Cephalopoda ; and my subsequent ob- 

 servations were confirmed by the theory of Dujardin. I have since 

 placed all my drawings and specimens at the disposal of Mr. Wil- 

 liamson of Manchester, who has given such a good earnest of what 

 he can do in elucidating the natural history of this group, by his 

 papers on Lugena and the Foraminiferous mud of the Levant. 



The observations which I have made on many hundred recent and 

 living specimens of various species, fully confirm Dr. Carpenter's 

 view as to the simple and homogeneous nature of the animal. His 

 idea of their reproduction by gemmation is also probably correct; 

 although I cannot agree with him in considering the granules which 

 are occasionally found in the cells as ova. These bodies I have fre- 

 quently noticed, and especially in the Lagencc ; but they appeared 



