Stromutoporoids and of Eozoon. 459 



In the presence of examples of Eozoon canadense with all 

 the details of their structure so perfectly preserved it is 

 amaziiii;- to iiiink that they lived at a time so distant that 

 evtn ihe Cambrian epoch with its highly organized fauna 

 does not seem very remote. 



Note 14. — In each colony of Eozoon the harizontal rouleaux 

 ladiate outwards from a dense vertical central sheaf composed 

 of strings of small Nummu itid shells without secondary 

 skeleton or with only very little. 



At a time wiien I was tieluded by theories of pressure and 

 by serpentine icjnes fatal, I had thought that this dense 

 central conical column or sheaf, seen in vertical sections 

 tiuough the centre, was produced by a crushing-in foree. 

 Tne resemblance between Er.zooa and, say, Stromatopora 

 coucentrlca is now seen to be very close. Each may be 

 compared to a huge hemispherical mushroom with a very 

 sn)ail stem. In Eozjou the main body is composed of small 

 disks limited in size owing to secondary deposit. In Stroma- 

 topoDi the usually larger coils or di^ks are not thus limited. 

 As^ain, in its plunu-like upwaid and outward growth the 

 Dawii Animal may he eon^.pared to a fountain. 



EXPLANATION OF THE PLATES. 



Platb XI. 



Fiff. 1. Stromatopora /iiipsfkii,'Bnvg. Devonian, Teignmouth. (P. 6328.) 



Polished slab. Tai geiitial view, >~ho\ving spiral systems. 



N;it. .-^ize. 

 Fii/. 2. Ilcematostroma epUcopale, Nich. (P. 5690 ) Polished slab. 



Tangential view, showing spiral sj'stems and central chambers. 



Nat. size. 

 Fig. 3. Actinostroma hehiurnense, Nich. Mid-Devonian, Teignmouth. 



A spiral systein. X 6. 

 Fiy. 4. Lahechia conferta, Lisnsdale. Very young specime.i, showing 



thin disk with coils. X 2. 



Plate XII. 



Fi(i. 5. Fozooncanadense,J)n\7i(m, Vertical section, showing alternating 

 light layers of calcite (supplementary skeleton) and dark 

 layers (which contain piles of Nuramulitid shells). Nat. size. 



Ft]/. 6. Eozoon canadense. Layers of coiled Nuaimulitid shells. The 

 calcareous supplementary skeleton has been dissolved by acid. 

 The shells lie in rouleaux in t!ie green areas (olivine and 

 serpentine) boui.ded by the supplementary skeleton, x 25. 



Fiij. 7. Eozoon canadense. A .'-ingle apparently broken-oll''Nummulitid 

 shell, showing funicular umbilicus, x 1 90. 



