PRE-CAMBRIAN LIFE 



67 



sented to us by the Huronian is that of a shore 

 deposit, formed under circumstances in which beds 

 of pebbles and sand were intermixed with the pro- 

 ducts of neighbouring volcanoes. Such a formation 

 is not likely to afford fossils in any considerable 

 number and variety, even if deposited at a time of 



Fig. 15. — Annelid Burrows^ Hastings Series , Madoc, 



I. Transverse section of Worm-burrow — magnified, as a transparent object. 

 («) Calcareo-silicious rock. (/') Spacefilled with calcareous spar, (r) Sand agglut- 

 inated and stained black. (d\ Sand less agglutinated and uncoloured. 2. Trans- 

 verse section of IVorm-burrow on weathered surface, natural size. 3. The same, 

 magnified. 



abundant marine life. It is therefore not wonderful 

 that we find little evidence of living beings in the 

 Huronian. In Canada I can point to nothing of 

 this kind, except a few cylindrical burrows, pro- 

 bably of worms (Fig. 15), and spicules possibly of 

 silicious sponges, which occur in nodules of chert 

 in the limestones, traces of laminated forms like 



