CAMBRIAN PERIOD 
And in their dart-like shells float on the main ; 
Seeking, when so they list, the depths again. 
But life in higher forms is in the throng : 
Leaf-footed shrimp forms crawl and swim along ; 50 
Active with jointed limbs about the sand, 
And sea-weed beds, that fringe the ocean strand. 
Here too are living one-eyed water-fleas, 
Shielded in shell against their enemies. 
Soft-bodied creatures in vast multitudes, 55 
Akin to King-crab forms, and Isopods, 
Haunt too the muddy bottoms : some as small 
As millet seeds, whilst other species crawl 
Longer than lobsters. Some have eyesight keen, 
Whilst others sightless wander o'er the scene. 60 
With easy movement do they creep about 
In shelly crusts, in three divisions wrought : 
And wide will these mixed Trilobites extend, 
Though destined be their vigorous race to end. 
New forms of life are seen upon the stage 65 
As onward roll the long years of the Age. 
In rocky beds "Sea-lilies," cup-shaped, grow ; 
Waving their arms in tidal ebb and flow. 
About the shoals star-fishes, five-rayed, glide 
(Are these some primal worms together tied ?) 70 
In quiet depths below the ocean swells, 
Predaceous Nautiloids, in long-coned shells, 
