458 Mr. R. Kirkpatiick on the Structure of 



Note 11. — Tlie umbilicus of each Nuramulitid sliell or coil 

 of Eozoon corresponds to the astrorhiza of Stroiuatoporoids. 

 Tiie umbilicus is fuiiiiel-sliaped, being broad at the j^roximal 

 end and reduced to a small pore at the distal. To obtain in 

 .Eozoon the same appearance as is seen on the surface of 

 Stromatopora it is necessary to cut a vertical section in the 

 plane of the flat surfaces of the Nummulitid shells. In 

 Evzoon each coil would be found to be small and surrounded 

 by a zone of supplementary deposit. Tlie daik radial streak-s 

 of the astrorhizaj of KStroniatoporoids are probably the expres- 

 i^ion of t!ie thick masses of snrcode ("? with iion) in the grooves 

 between surface-tubercles of the coils of cliaiubers. 



Sole 12. — Possibly the little " buds " seen on the Nummu- 

 litid shells of Eozoon may result from a process of agamooony. 

 See the beautiful figures of Peneroplis pertusus in F. W. 

 Winter's remarkable study of the Tlialamophoren {' Pro- 

 tistenkunde,' x. 1907, p. 1, pi. i. tig. 1). Probably thin 

 sections of Eozoon will reveal some very interesting facts. 



Note 13. — The rouleaux of Nummulitid shells are serpentine 

 in a double sense. The existence in Eozoon of bands of 

 dolomite or secondary calcite alternating with bands of 

 olivine or serpentine results, I think, from the following 

 causes : — The supplementary skeleton (calcite or dolomite) 

 originally formed masses of pure calcite with very little 

 jjrotoplasm in it, but the coils of shells were full of proto- 

 plasm containing metallic compounds. There would be a 

 great difference in the molecular changes and affinities in the 

 primary and secondary skeletons, and in the former the silica 

 would much more easily combine with the iron-magnesian 

 coiupounds to form olivine. The reasonableness of this theory 

 is shown by the fact that the canal-system permeating the 

 secondary skeleton is wonderfully preserved in olivine and 

 can l)e etched out by dissolving the calcite. 



Eozoon may be regarded as a marvellous uature-print by 

 "Nature herself', and one beside which the most refined products 

 of human art are clumsy, for the finest details of the 

 structure of the skeleton have been preserved. During each 

 " process '^ the parts have been changed molecule by molecule. 

 It is true the resulting work of "art" has been woefully 

 damaged in the case of Eozoon vesuvii, E. bavancnm, &c. by 

 later rough treatment, such as heat, pressure, and crumpling. 



In E. vesuvii the extra baking has converted the olivine 

 into a serpentine almost resembling tha granular Cornish 

 kind, but the original Nuniuuilitid pattern is still obvious. 



