FORAMINIFERA AND RADIOLARIA. 



103 



494. Whilst essentially belonging to the Nummuline group, in virtue 

 of the fine tribulation of the shelly layers forming the ' proper wall ' of 

 its chambers, Eozoon is related to various types of recent Foraminifera 

 in its other characters. For in its indeterminate zoophytic mode of 

 growth, it agrees with Polytrema ( 483); in the incomplete separation 

 of its chambers, it has its parallel in Carpenteria ( 481); whilst in the 

 high development of its 'intermediate skeleton' and of the 'canal-sys- 

 tem ' by which this is formed and nourished, it finds its nearest represen- 

 tative in Calcarina ( 484). Its calcareous layers were so superposed, one 

 upon another, as to include between them a succession of ' storeys ' of 

 chambers (Plate xvn., fig. 1, A 1 , A 1 , A a , A 2 ); the chambers of each 'storey' 

 usually opening one into another, as at a, a, like apartments en suite; 

 but being occasionally divided by conrolete septa, as at I. 5. These septa 

 are traversed by passages of 



communication between the F- 344 - 



chambers which they separate; 

 resembling those which, in 

 existing types, are occupied 

 by stolons connecting together 

 the segments of the sarcode- 

 body. Each layer of shell * 

 consists of two finely-tubulat- 

 ed or ' nummuline ' lamellae, 

 B, B, which form the boun- 

 daries of the chambers be- 

 neath and above, serving (so 

 to speak) as the ceiling of the 

 former, and as the^oor of the 

 latter; and of an intervening 

 deposit of homogeneous shell- 

 substance c, c, which consti- 

 tutes the ' intermediate ske- 

 leton. ' The tubuli of this Vert . cal Sect . on of a n one Calcareous 



6 nummuline layer (Fig. 344) lamellae of Eozoon Canadense:-^ a, Nummuline layer, 

 nvo nQnnllir -filler! nr ffta in perforated by parallel tubuli, which show & flexure along 



aie usually n j^as mf he Une a , y ; beneath this is seen the inte nnediate 



the N UmmullteS OI the num- skeleton, e, c, traversed by the large canals, 6, 6, and by 

 mulitip limestone') by min- fflSSl^ 8 ^ PlanCS ' ^ich extend also into the Num- 



eral infiltration, so as in 



transparent sections to present a fibrous appearance; but it fortunately 

 happens that through their haying in some cases escaped infiltration, the 

 tabulation is as distinct as it is even in recent Kummuline shells (Fig. 

 344), bearing a singular resemblance in its occasional waviness to that of the 

 Crab's claw ( 613). The thickness of this interposed layer varies con- 

 siderably in different parts of the same mass; being in general greatest 

 near its base, and progressively diminishing towards its upper surface. 

 The 'intermediate skeleton' is occasionally traversed by large passages 

 (D), which seem to establish a connection between the successive layers 

 of chambers; and it is penetrated by arborescent systems of canals (E, E), 

 which are often distributed both so extensively and so minutely through 

 its substance, as to leave very little of it without a branch. These canals 

 take their origin, not directly from the chambers, but from irregular 

 lacuncB or interspaces between the outside of the proper chamber-walls 

 and the 'intermediate skeleton,' exactly as in Calcarina ( 484); the ex- 

 tensions of the sarcode-body which occupied them having apparently 



