14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



the west, the sediments of which are buried beneath later strata or 

 are off the present shore line of the continent beneath the sea. 



The theory that life originated and developed in fresh-water ponds 

 and lakes does not appeal to me. More uniform conditions of tem- 

 perature and environment would be present in the ocean and the 

 sediments of the fresh-water deposits of pre-Cambrian and Cambrian 

 time, if such exist, do not show sufficient evidence of life having 

 existed at the time of their deposition. The Algonkian fossils of the 

 Belt and Grand Canyon series [Walcott, 1899, pp. 227-239] prob- 

 ably came from the marine fauna when a temporary connection ex- 

 isted between the interior fresh- or brackish-Avater lakes and the 

 ocean. 



RESUME 



1. Life probably first developed in the open ocean, as outlined by 

 Brooks [1894]. 



2. The life of the oceans became adapted to littoral and shore 

 conditions in Algonkian time during a period when the relation of 

 all the continents to sea level was essentially the same as at the 

 present time, or the continents may have been still more elevated in 

 relation to the surrounding oceans. 



3. The period of Algonkian continental elevation was of sufficient 

 duration to permit of the development along the shores and shelves 

 of the continents of the types of life now found in the basal Cam- 

 brian rocks, but the sediments containing the record of this life are 

 probably concealed beneath the present oceans. 



4. The known fossils contained in the Algonkian sediments of the 

 Cordilleran geosyncline lived in fresh or brackish waters that were 

 rarely in connection with marine waters on the margins of the 

 Algonkian continent of North America. This will explain the abrupt 

 appearance of a highly specialized crustacean deep down in the 

 Belt series. 



5. When the oceanic waters gained access to the Algonkian conti- 

 nental areas at the close of that era they brought with them the 

 littoral fauna which had been developed during the Lipalian sedi- 

 mentation,^ and buried its remains in the sands and muds which 

 form the Lower Cambrian deposits. 



^Lipalian (/l«7r«-|-a/if ) is proposed for the era of unknown marine sedi- 

 mentation between the adjustment of pelagic life to littoral conditions and 

 the appearance of the Lower Cambrian fauna. It represents the period be- 

 tween the formation of the Algonkian continents and the earHest encroach- 

 ment of the Lower Cambrian sea. 



