1866.] KING AND ROWNET " EOZOONAL ROCK*" 189 



charoidal calcite was originally the amorphous calcareous substance 

 composing the septa which bounded or formed the " chambers " that 

 were occupied by its sarcode-segments ; while the granules of ser- 

 pentine are '^casts'' of the '* chambers" themselves. According to 

 Sterry Hunt, " the vacant spaces left by the decay of the sarcode 

 may be supposed to have been filled by a process of infiltration, in 

 which the silicates were deposited from solution in water, like the 

 silica which fills up the pores of wood in the process of silicification"*. 



Considering the scattered and laminar modes of arrangement oi 

 the " chamber-casts," it is conceived that *' Eozoon Canadense " be- 

 came enlarged by the irregular heaping up or " acervuline " growth 

 of the *' sarcode-segments," as well as by their having grown in suc- 

 cessive layers one upon another. On this view the calcareous septa, 

 enclosing the sarcode-segments, formed a vesicular skeleton, its cavi- 

 ties affecting an "acervuline," or a laminar arrangement. 



The calcareous septa are in some instances extremely thin, and in 

 others of considerable thickness. In the latter state they have been 

 described as consisting of two distinct portions. One of them, con- 

 sidered to have been the immediate covering of the sarcode sub- 

 stance, occurs as a thin fibrous or" asbestiform layer," the fibres 

 passing from surface to surface — peculiarities which have given rise 

 to the idea that the layer was originally the homologue of the finely 

 tubulated "proper wall" characteristic of the skeleton of iVwrnrnw- 

 lina, Operculina, Calcarina, and other allied foraminiferal genera, 

 and consequently that the fibres are casts of tubules, such passages 

 having served for the extrusion of fine thread-like " prolongatio-ns," 

 called pseudopodia, from the " sarcode-segments : " the other portion, 

 usually the thickest, and designated, from its position and other con- 

 siderations, the " intermediate skeleton," contains imbedded in its 

 substance (this is particularly the case in Canadian Ophite) a variety 

 of branching and other structures, which are regarded as " internal 

 casts" of tubular passages, such as are known to constitute the 

 " canal system " (similarly circumstanced, and occupied by thickish 

 " prolongations of the sarcode-substance ") of the foraminifers above 

 mentioned. Certain of these structures, also some of the elongated 

 constrictions already noticed, are supposed to be casts of passages 

 occupied by " stolons," which connected both vertically adjacent and 

 laterally adjacent " sarcode-segments." 



When specimens of " eozoonal " rock are carefully digested in a 

 weak solution of hydrochloric acid, the calcite may be completely 

 dissolved out, leaving vacant passages which wind about amidst the 

 undissolved granules and plates or " chamber- casts." As the branch- 

 ing structures imbedded in the septa are insoluble in this menstruum, 

 like the latter parts they remain intact in the passages. Frequently, 

 also, the surfaces of the granules may be seen crowded with aciculi 

 — the so-called casts of the pseudopodial tubuli of the " proper wall." 



At first our investigations were not attended with much success. 



* Quart. Joum. G-eol. Soc. vol. xxi. p. 67. Dr. Dawson adopts a similar view, 

 — that the matter of the chamber-casts was "introduced by infiltration or as se- 

 diment" {op. cit. p, 52). Dr. Carpenter, however, holds a different view, which 

 will be noticed hereafter. 



