On the Structure and Position of Eozoon Ganadense. 291 



Interpreting the copious information which we derive 

 from these two sources, by the knowledge we already possess 

 of the life-history of existing Foraminifera, we find ourselves 

 able to reconstruct our Eozoon with at least as much certainty 

 as the comparative anatomist can restore an Iguanodon or a 

 Plesiosaurus. And as the greater part of the details on which 

 this reconstruction rests have been already recorded in the 

 form and order in which they have actually presented them- 

 selves to Dr. Dawson and myself,* I prefer, that the present 

 description, and its accompanying figures, should place the 

 creature before my readers as it existed in life, whilst building 

 up in the ancient sea-beds those massive reefs which formed 

 the materials of the Laurentian limestones. 



The calcareous skeleton or shell of Eozoon might be 

 likened to a building made up of successive tiers of chambers 

 (TJncoloured Plate, Fig. 1) ; the chambers A 1 , A 1 , A 1 , and 

 A 3 , A 2 , of each tier, however, communicating very freely 

 with each other, so that the segments of the sarcodic layer 

 which occupied them were intimately connected, as is shown 

 by the continuity of their siliceous models (Coloured Plate). 

 In most existing Foraminifera, the successive chambers 

 communicate only by narrow orifices, so that the segments 

 of the body which occupies them are mutually connected 

 by slender bands or stolons : but in Oarpenteria we have 

 an example of a communication nearly as free as that which 

 exists between the chambers of the same tier in Eozoon; 

 and I have occasionally met with chambers as completely 

 isolated from the rest as are those of Foraminifera generally, 

 the communication being established by several narrow pas- 

 sages (TJncoloured Plate, Fig. 1, h, b), exactly corresponding 

 to those which I have described in Gycloclypeus. Moreover, I 

 not unfrequently find, projecting from the surfaces of the prin- 

 cipal layers, little groups of comparatively small segments, 

 which have budded-forth from the larger ones, and which 

 might almost be taken for internal casts of Globigerince or 

 other small separate Foraminifera. 



The propel walls of the chambers are everywhere formed 

 of a pellucid, vitreous shell-substance, minutely perforated with 

 tubuli, so as exactly to correspond with those of Nummulites, 

 Operculinoe, etc. These tubuli, as in the existing representa- 

 tives of the Nummuline series, usually run parallel to each 

 other, passing directly from the inner to the outer surface of 

 the chamber-wall (TJncoloured Plate, Fig. 1, b, b), without 

 coalescence or ramification; and the siliceous casts of the 

 cavities of these tubules often remain in situ after the removal 



* See the Quarterly Journal of the Geological Society, February, 1865, 

 pp. 51— 66. 



VOL. VII. — NO. IV. « U 



