176 



THE DAWN OF LIFJS. 



or have been given ; and I now merely add (in fig. 49) 

 a magnified camera tracing of a portion of a lamina 

 of Eozoon with its canals and tubuli, to show more 

 fully the nature of the structures in controversy. 



FIG. 49. Portion of a thin Transverse Slice of a Lamina of Eozoon, 

 magnified, showing its structure, as traced with the camera. 



(a.) Nummuline wall of under side. (&.) Intermediate skeleton with canals, 

 (a'.) Nummuline wall of upper side. The two lower figures show the lower 

 and upper sides more highly magnified. The specimen is one in which the 

 canals are unusually well seen. 



It may be well,, however, to sum up the evidence as 

 it has been presented by Sir W. E. Logan, Dr. Car- 

 penter, Dr. Hunt, and the author, in a short and in- 

 telligible form ; and I shall do so under a few brief 

 heads, with some explanatory remarks : 



1. The Lower Laurentian of Canada, a rock forma- 



