1866.] CAKPENTEE — EOZOON CANALENSE. 221 



accounted for by inorganic agencies, there remains the T^nmmuline 

 structure of the chamber-walls, to which — I venture confidently to 

 assert — no parallel can be shown in any undoubted mineral product*. 

 The " asbestiform layer " obtained by the decalcification of the 

 Nummuline shell-wall, which sets free the siliceous internal casts 

 of its tubuli, presents a series of remarkable variations, which can 

 be closely paralleled by the variations existing in the course of the 

 tubuli in the shells of living Nummuline Foraminifera. What we 

 may consider the normal arrangement is the passage of the tubuli 

 in a straight and parallel course from the internal to the external 

 surface of the shell-wall ; and this is represented in Eozoon by a 

 regular disposition of the acicular fibres, which stand side by side, 

 like the filaments that form the pile of velvet, their lower ends resting 

 on the subjacent segment, whilst their upper form a uniform surface 

 so close in texture as to be scarcely resolvable into the points of its 

 constituent aciculif. But, as is often the case in OperculinaX, the 

 tubuli may depart from their normal parallelism, separating from each 

 other in some parts, and becoming more closely crowded in others ; 



* It may be thought a matter for regret that, before putting themselves in a 

 position of antagonism to those who have made a special study of the minute 

 structure of Foraminifera, Profs. King and Eowney should not have availed 

 themselves of the opportunity pubhcly offered them some months since (see the 

 ' Keader ' for July 8th, 1865) of inspecting my preparations of Eozoon. I have 

 recently learned from personal communication with Prof. Eowney, not only 

 that he had no practical knowledge of the structure of Nnmmuline shells, but 

 that he had not, until I myself showed them to him, ever seen any transparent 

 sections of Eozoon thin enough to give a good view of its tubuliferous layer, — 

 his observations having been almost exclusively made upon decalcified specimens. 

 And it is obviously from this limitation to one method of inquiry, that Profs. 

 King and Eowney have fallen into what I feel able to demonstrate to be the 

 fundamental error of their whole treatment of this part of the subject, — the 

 assumption that the " asbestiform layer " is, in its original state, before having 

 been acted on by acid, a mere bundle of siliceous fibres, instead of being (as I 

 maintain) a continuous layer of calcareous shell, the vertical tubuli of which 

 have been filled up by the substitution of siliceous deposit for the threads of 

 animal matter which originally occupied them. If they had made the experi- 

 ment, which I have over and over again repeated, of subjecting a very thin 

 transparent section of Eozoon, cemented on glass by Canada balsam, to the 

 action of dilute acid, they would have been at once convinced by the complete 

 alteration in the appearance of this layer, that a transparent substance inter- 

 vening between the asbestiform fibres and cementing them together, has been dis- 

 solved out. This becomes still more obvious where the fibres diverge from one 

 another in some parts and converge in others, as will be described in the next 

 paragraph. 



t It is apparently from this continuity of the external surface of the asbesti- 

 form layer, that Profs. King and Eowney have been led to the inference that its 

 fibres are so closely compacted together that there is no room for any intervening 

 calcareous cement. But if they had been familiar with the study of living 

 Foraminifera, they would have been aware that the pseudopodia which have 

 passed through the pores of the shell, coalesce on its external surface into a con- 

 tinuous layer of sarcode ; so that the continuity of the external surface of the 

 asbestiform layer is precisely what we should expect, if this layer represents the 

 filamentous extensions of the original sarcode-body of the animal. A still more 

 remarkable representation of this sarcodic layer in the siliceous model of the 

 animal of Eozoon will be presently described. 



I See Memoir on Operculina in the Phil. Trans, for 1859, p. 54, and Plate iv. 

 figs. 2, 4, 11. 



