44 RELICS OF PRIMEVAL LIFE 



show, giant cuttle-fishes, destitute of shells, were then 

 the tyrants of the sea, but are represented only by 

 the markings of their long and muscular arms on 

 the soft sea mud while dashing after their Crus- 

 tacean prey. What I desire, however, chiefly to 

 emphasize is, that in the lowest beds of the 

 Cambrian we have evidence of sea-bottoms swarm- 

 ing with representatives of all the leading t)'pes 

 of marine invertebrate life, and therefore seem to 

 be still far from the beginning of living things, if 

 that was a slow and gradual process, rather than a 

 sudden or rapid series of events. 



