162 J. J. LISTER. 



and the others follow in concentric rings, but the innermost 

 ring is less completely divided up into cubical chambers than 

 those which follow. 



As in the megalospheric forms described above, a large 

 nucleus is present. In the large specimen it lies in the second 

 chamber (fig. 52), and is nearly spherical, measuring about 85 fi, 

 in diameter. In the other, of which sections were cut, it lies in 

 the megalosphere, and has an oval shape, measuring 60 x 40 fi. 

 In section (fig. 54) it presents the appearance of a close reti- 

 culum with dark masses of different sizes embedded in it, and 

 is surrounded by a dark line which clearly separates the nucleus 

 from the coarse reticulum of the protoplasm. This obscure 

 structure of the nucleus is no doubt due to the imperfect 

 preservation. 



3. Concluding Remarks. 



From the evidence now presented, it appears that the 

 following statements relating to the life-history of the Forami- 

 nifera may be accepted. 



1. The species of Foraminifera are in a great number of 

 cases dimorphic. Relying on the difference in size of the central 

 chambers of the shells, the dimorphism has been stated to exist 

 in four out of the ten families into which Brady divided the 

 group. This is shown in the following table : — 



