1864. ] CAKPENTEE STRUCTTJKE OE EOZOON. 61 



separation of the chambers has been as complete as it is in Forami- 

 nifera generally; and the communication between them is then 

 established by several narrow passages (PI. YIII. fig. 2) exactly 

 corresponding with those which I have described and figured in 

 Cydochjpeus *. 



Diagram illustrating the Structure of Eozoon. 



||j|j||||]||]|,||lli|||||piijj||jl|||'|i|l||ill^ 



\^ B 



B 



\^^^wm 



^^lf|P^'^y,^^.^^'''/,,^«.^ '//] 



'III 



A', A', A'. Tliree chambers of one layer, communicating with each other directly 



at a, and by three passages through a shelly partition at h. 

 A}^, A2, A2. Three chambers of a more superficial layer. 



B, B, B. Proper wall of the chambers, composed of finely-tubular shell-substance. 



C, C, C. Intermediate or supplemental skeleton, traversed by D, D, a stolon of 



communication between two chambers of different layers, and by 

 E, E, canal-system originating in the lacunar space F. 



The mode in ivJiicIi each successive layer originates from the one 

 which has preceded it, is a question to which my attention has been 

 a good deal directed ; but I do not as yet feel confident that I have 

 been able to elucidate it completely. There is certainly no regular 

 system of apertures for the passage of stolons giving origin to new 

 segments, such as are found in all ordinary Polythalamous Forami- 

 nifera, whether their type of growth be rectilinear, spiral, or cycli- 

 cal ; and I am disposed to believe that where one layer is separated 

 from another by nothing else than the proper walls of the cham- 

 bers, — which (as I shaU presently show) are traversed by multitudes 

 of minute tubuH giving passage to pseudopodia, — the coalescence of 

 these pseudopodia on the external surface would suifice to lay the 

 foundation of a new layer of sarcodic segments. But where an in- 

 termediate or supplemental sTceleton, consisting of a thick layer of 

 solid calcareous shell, has been deposited between two successive 

 layers, it is obvious that the animal body contained in the lower 

 layer of chambers must be completely cut ofi^ from that which occu- 

 pies the upper, unless some special provision exist for their mutual 



* Op. cit. p. 294. 



