NEBULA TO MAN 
Breathing through gills when in the tide they lie ; 
Through lungs when ebbing water leaves them dry. 
From some old ganoid grandsire are they sprung, 
Whose swimming bladder slowly turned to lung ? 
And are these double-breathers on the way 25 
To found amphibian life of later day ? 
Though thickly swarm some finny groups around, 
By checks and limitations are they bound. 
Dog-fish and Shark-like creatures, numerous grown, 
Play well their part, and keep the small fry down. 30 
And many orders here would cease to be, 
Had they not safety in fecundity. 
Although of their superiors the prey, 
The lower orders of the watery way 
Crowd far and wide, in forms both new and old. 35 
But some are losing fast their former hold. 
The Trilobites' once large and varied hosts 
Show signs of waning now along the coasts. 
The box-like cystoids too are on the wane, 
To bud-shaped blastoids yielding their domain, 40 
Nor can the graptolites their place retain. 
Conditions change ; and those that cannot meet 
The altered state are driven to retreat. 
There is no standing still when comes the stress, 
And those that make no headway retrogress. 45 
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