Dr. Carpenter, who in admirable papers, which I need not quote here,[52] has illustrated in detail the structures of Eozoon, and shown its resemblance to modern forms, places Eozoon as a generalized type between the Nummuline and Rotaline groups of Foraminifera. It resembles the former in its fine and complicated tubulations, and some of the larger sessile forms of the latter in its habit of growth. More especially, this is near to that of the genera Carpenteria and Polytrema. In the former, more especially, there are a number of somewhat flattened calcareous cells with perforated walls, and built up in a conical form around a central pipe or funnel into which the apertures of the cells open. A specimen of Carpenteria, enlarged and having the walls of its cells thickened by a supplemental tubulated deposit like that of Calcarina, would approach very near to Eozoon. [Footnote 52: I may specially refer to the following:-- W. B. Carpenter on _Eozoon Canadense_. _Intellectual Observer_, No. xl., p. 300, 1865. Supplemental notes on the structure and affinities of _Eozoon Canadense_, _Quart. Journ. Geol. Soc._, Lond. Vol. xxii., pp. 219-228, 1866. Notes on the structures and affinities of _Eozoon Canadense_. _Canad. Nat._, new ser., vol. ii., pp. 111-119, wood-cut, 1865. A reprint from _Quart. Journ. Geol. Soc._, Lond., 1865. Further observations on the structure and affinities of _Eozoon Canadense_. In a letter to the President. _Proc. Roy. Soc._, Lond., vol, xxv., pp. 503-508, 1867. New observations on _Eozoon Canadense_. _Ann._ and _Mag. Nat. Hist._, sen 4, vol. xiii., pp. 456-470, one plate, 1874. Final note on _Eozoon Canadense_. _Ann._ and _Mag. Nat. Hist._, ser. 4, vol. xiv., pp. 371-372, 1874. Remarks on Mr. H. J. Carter's letter to Prof. King on the structure of the so-called _Eozoon Canadense_. _Ann._ and _Mag. Nat. Hist._, ser. 4, vol. xiii., pp. 277-284, with two engravings, 1874.]