1866.] CARPENTER — EOZOON CAlfADENSE. 219 



2. Supplemental Notes on the Strtjcttjee and Affinities of Eozoon 

 Canadense. By William B. Caepenteb, M.D., F.E.S., F.G.S. 



Since the date of my communication to the Geological Society made 

 through Sir William Logan, upon the remarkable fossil discovered 

 by him in the Laurentian rocks of Canada, I have given a consider- 

 able amount of time and attention to the further investigation of ita 

 characters ; and I am desirous of recording certain additional fea- 

 tures in its structure, which seem to me to strengthen the view ori- 

 ginally put forward by Dr. Dawson, and confirmed by my own in- 

 quiries, of its Poraminiferal affinities. 



It will be remembered that this view was originally propounded 

 by Dr. Dawson as the result of his investigations (1) into the re- 

 lations of the calcareous and siliceous layers, which appeared to him 

 to indicate that a chambered calcareous skeleton had been in- 

 filtrated by silicates in solution, so as to leave a siliceous * deposit 

 in the spaces previously occupied by the animal body ; and (2) into 

 the distribution of an arborescent " canal-system " which he de- 

 tected in the calcareous skeleton, bearing a most remarkable re- 

 semblance to the canal- system described by myself in Calcarinaf. 



My own observations upon the specimens placed in my hands by 

 Sir W. Logan supplied an important confirmation to this view, for 

 these disclosed the fact that the proper luall of the chambers, when 

 well preserved, exhibits the finely tubular structure of the Num- 

 muHne Foraminifera ; which is demonstrable as well in thin 

 transparent sections J, as in decalcified specimens, which show the 

 siliceous casts of the interior of the chambers to be covered with a 

 thin " asbestiform layer " composed of acicular fibres standing upon 

 end, usually parallel to each other §. These fibres I regard as the. 

 internal casts of the tuhuU of the shelly layer, which were originally 

 occupied by minute filaments (pseudopodia) proceeding from the 

 sarcodic body of the animal. And I feel justified in doing so by the 

 fact that a recent siliceous cast of an Anvphistegina from which the 

 shell has been removed by decalcification, kindly presented to me by 

 my friend Mr. "W. K. Parker, affords a perfect representation of this 

 " asbestiform layer " — the only difference being that the fibres are 

 larger and more separate, in accordance with the characteristic 

 tubulation of the shell in this genus. This cast gives a perfect 

 model in a green silicate (glauconite?) of the lobes of the body, of the 

 canal- system, and of the tubuli of the shell- wall ; and as the shell 

 within which it was formed was brought up with many similar ones 

 by Mr. Jukes in his dredgings on the Australian coast, it is obvious 

 that the complete replacement of the segments of the animal body 



^ I use the term siliceous, here and elsewhere, to mean compounds of which 

 silicic acid is the characteristic ingredient. 



t Compare Dr. Dawson's delineations of the canal-system of Eozoon Cana* 

 dense, in Quart. Journ. Gaol. Soc. vol. xxi. Plate vii. figs. 3 (a a) and 6, with 

 the representations of the canal-system of Calcarina in my * Introduction to 

 the study of the Foraminifera,' Plate, xiv. figs. 4, 8, 9. 



:j: Quart. Journ. Greol. Soc. vol. xxi. Plate viii. figs. 4 «, 4 J. 



§ Op. cit. Plate ix. fig. 4. 



r2 



