518 



own observations are in favour of it — the circumstance will go far to 

 sustain our "objection;" inasmuch as there is required in "Eozoon" a 

 vacancy to hold a " layer of sarcode ;" whereas, in the cases to which 

 we referred (and we are acquainted with a number of others), there 

 exists no representative of the kind, either in the form of a" siliceous 

 layer," or anything else ; the space between two " chamber casts," that 

 rest one upon the other, being crossed by and filled up with continuous 

 aciculi.* We did not, when adducing this point, regard it in a 

 stronger light than a difficulty : it was not urged as a positive argu- 

 ment on our side ; but we now do so ; and, at the same time, we chal- 

 lenge its subversion. 



Reflecting on all the evidences and arguments given in this and our 

 former Paper in connexion with the " proper wall," we feel certain 

 that the original description we gave of it is the only published one that 

 can be said to be correct ; and we are thoroughly convinced that our view 

 of its nature is incontrovertible. It is a feature composed of juxtaposed 

 as well as separated aciculi : it is part and parcel of the ' ' chamber 

 casts," being mineralogically an allomorph of their component serpen- 

 tine : added to which, the " fact" last brought forward shows clearly that 

 no unquestionable evidence can be adduced in favour of the belief, that 

 the " nummuline layer" is the representative of the pseudopodial or 

 tubulated cell wall of a foraminifer ; for, as such, it would in number- 

 less cases have been functionally useless, f 



b. "Intermediate Skeleton.'''' — We have nothing of importance to add 

 to our former remarks on this part ; nor, from the absence of any evi- 

 dence or argument against us, is anything more required to sustain the 

 view we hold of its being identical with the matrix containing grains 

 of pargasite, &c, in various crystalline rocks. 



c. " Chamber Casts? — Referring to what is stated in our former Paper 

 respecting the isolated grains of coccolite and other minerals in Tyree 

 marble, also those of chondrodite in the crystalline limestone of New 

 Jersey, being strictly analogous to the " chamber casts of Eozoon," Dr. 

 Dawson commences one of his arguments by stating, that 44 if all speci- 

 mens of Eozoon were of the acervuline character, the comparisons of the 

 chamber casts with" such grains " might have some plausibility. But 

 it is to be observed that the laminated arrangement is the typical one. J 



On what ground does Dr. Dawson make the last statement ? The 

 same question equally applies to a similar one made by Dr. Carpenter. 

 A character to be " typical" must be general; but the "laminated ar- 

 rangement," although often beautifully developed in specimens from 



* " Popular Science Review," vol. iv, PI. XV., Fig. 10 (Carpenter, and Rupert- Jones). 



f It must not be overlooked that the "elongated bundles" with " tangentially" ar- 

 ranged fibres, to which Dr. Carpenter has " seen no parallel in other Foraminifera," equally 

 show the impossibility of the " nummuline layer" being an organic production. 



X " Quarterly Journal of Geological Society," vol. xxiii., p. 263. Dr. Giimbel, like 

 ourselves, has identified the grains of coccolite and pargasite, respectively occurring in 

 the crystalline limestones of New Jersey and Finland, with the "chamber casts." Why 

 is our case no more than a plausible comparison ? 



