328 Royal Society : — 



sarcode-body, by the agency of which the calcareous substance of thi9 

 intermediate skeleton seems to have been deposited. The distribution 

 of this canal-system, although often well displayed in transparent 

 sections, is most beautifully shown (as in Polystomella *) by the 

 siliceous casts which are left after the solution of the shell, these casts 

 being the exact models of the extensions of the sarcode-body that 

 originally occupied its passages. 



In those portions of the organism in which the chambers, instead 

 of being regularly arranged in floors, are piled together in an " acer- 

 vuline " manner, there is little trace either of" intermediate skeleton" 

 or of " canal-system "; but the characteristic structure of their proper 

 walls is still unmistakeably exhibited. 



Whilst, therefore, I most fully accord with Dr. Dawson in referring 

 the Eozoon Canadense, notwithstanding its massive dimensions and 

 its zoophytic mode of growth, to the group of Foraminifera, I am 

 led to regard its immediate affinity as being rather with the Num- 

 muline than with the Rotaline series — that affinity being marked 

 by the structure of the proper wall of the chambers, which, as I have 

 elsewhere endeavoured to show t, is a character of primary impor- 

 tance in this group, the plan of growth and the mode of communica- 

 tion of the chambers being of secondary value, and the disposition of 

 the "intermediate skeleton" and its "canal-system" being of yet 

 lower account. 



I cannot refrain from stopping to draw your attention to the fact 

 that the organic structure and the zoological affinities of this body, 

 which was at first supposed to be a product of purely physical opera- 

 tions, are thus determinable by the microscopic examination of an 

 area no larger than a pin-hole — and that we are thus enabled to 

 predicate the nature of the living action by which it was produced, 

 at a geological epoch whose remoteness in time carries us even be- 

 yond the range of the imagination, with no less certainty than the 

 astronomer can now, by the aid of "spectrum analysis," determine 

 the chemical and physical constitution of bodies whose remoteness in 

 space alike transcends our power to conceive. 



The only objections which are likely to be raised by palaeontologists 

 to such a determination of the nature of Eozoon, would be suggested 

 by its zoophytic mode of growth, and by its gigantic size. The first 

 objection, however, is readily disposed of, since I have elsewhere 

 shown X that a minute organism long ranked as zoophytic, and de- 

 scribed by Lamarck under the designation Millepora rubra, is really 

 but an aberrant form of the Rotaline family of Foraminifera, its 

 peculiarity consisting only in the mode of increase of its body, every 

 segment of which has the characteristic structure of the Rotalince ; 

 and tiius, so far from presenting a difficulty, the zoophytic character 

 of Eozoon leads us to assign it a place in the Nummnline series exactly 

 corresponding to that of Polytrema in the Rotaline. And the ob- 

 jection arising from the size and massiveness of Eozoon loses all its 

 force when we bear in mind that the increase of Foraminifera 



* Phil. Trans. 1860, plate xviii. fig. 12. 



f Introduction to the Study of the Foraminifera, chap. iii. { Ibid. p. 235. 



