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POPULAR SCIENCE REVIEW. 
end, and by repeated forking and joining these rods give rise 
to ten plates of a delicate calcareous network, which are arranged 
in two cross rings of five plates each (woodcut b). Passing back- 
joints ; C. Pentacrinoid larva. 
wards from beneath the centre of the lower ring of plates is a 
series of delicate calcareous rings, which become supported, later 
on, by bundles of longitudinal rods forming inside them. The last 
* We are indebted to the courtesy of Sir John Lubbock for permission 
to use this woodcut. 
