Page:The Scientific Monthly vol. 3.djvu/333

 ORIGIN AND EVOLUTION OF LIFE

��327

��From the Burgess fauna it appears that the invertebrateB bad en- tered all the life zones of the continental and oceanic waters except possibly the abyssal. All the principal phyla — the segmented Aunu- lata, the joined Arthropoda (including trilobites, merostomes, cms-

��ill

���Pio. 10. Lira ZONBB or Ciubbun ihd Bbl,itbd diaxiNa iHTBBiBBBma. Chart BhowlDg the contrast between the Uld-Cambrlan (lelt) and recent (right) pb^ln Br Rot W. Miner.

��taceans, arachnids, and insects), medusee and other coelenterates, echi- nodenns, brachiopodsj molluscs (including pelycypods, gastropods, am- monites and other cephalopods), and sponges — were all clearly estab- lished in pre-Camibrian times. Which one of these great invertebrate

���Life Zonbb or Invebtbdbateh, Cohpibsd 1 RiFTiLiB. BiBDa IND Mahualh. Cbart ebowlDg the eitenaloD bratea and iDTertebratea tbrongbouC the Tarlous babEtat lODea.

�� �