PRE-CAMBRIAN LIFE 71 



able to verify his Radiolarians and sponges as well. 

 Matthew's observations in New Brunswick in any 

 case establish their probability. Giimbel also re- 

 cognises a species of Eozoon in the equivalent rocks 

 of Bavaria (see p. 213). 



It is evident that here we have approached the 

 limit of the higher forms of marine invertebrate 

 life, having as yet nothing to show except worms 

 and Protozoa. It is to be observed, however, that 

 there may be somewhere Huronian deposits formed 

 in deep and quiet waters, which may give better 

 results, and that the unconformity between the 

 Huronian and overlying Kewenian may indicate a 

 lapse of time, of which monuments may yet be found. 



The Laurentian. 



Last of all we have the widely distributed Lau- 

 rentian system of Logan, the oldest known to 

 geologists, and which with the Huronian constitutes 

 the great Archaean group of formations of Dana and 

 others. In its lowest part this consists entirely of 

 the stratified granitic rock known as gneiss, inter- 

 bedded in some places with dark-coloured crystalline 

 rocks or schists. This may be a part of the first- 

 formed crust of our globe, produced under conditions 



