This blastema then begins to change, and gradually assumes the form of the perfect echinoderm.
"On the Origin and Metamorphoses of Insects"
Sir John Lubbock
And, as a question of development, the formation of the radiate echinoderm within its vermiform larva seems to me to be analogous to the formation of a radiate Medusa upon a Hydrozoic stock.
"Critiques and Addresses"
Thomas Henry Huxley
The fossil records of the long ages during which the Mollusc, the Crustacean, and the echinoderm slowly assumed their characteristic forms are hopelessly lost.
"The Story of Evolution"
Joseph McCabe