[120]

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American Journal of Science (n.s.) vol. III. New Series

p. 337 J. D. Dana on Zoophytes.

"The institution of these various groups (ie classes orders genera &c) is not properly classifying, for the classification is completed, when the branchings & interlinkings of affinities are made out…Genera are convenient artificial sections, based on natural affinities; & very commonly they made almost imperceptibly into one another...It may often have seemed vexatious to the systematist to have had a well characterized family or genus spoiled in its characteristic & exceptions introduced by the discovery of a new species, which blend it with another & previously distinct group"

[121]

(6) p. 340 do. It seems at first a violation of all propriety to arrange together animals having gills & those that have none; those that have a heart, & those that are destitute of even a trace of one, beyond a distinct valve or two in the circulatory system; those that have distinct arteries & those whose arteries are only lacunal passages among the muscles & other organs." … The class Crustacea actually illustrates each of the anomalies just stated. If Amphioxus be a Fish, we may have a vertebrate animal without a brain & without a sense to raise it above a Polyp.

[James D. Dana. 1847. On Zoöphytes, No. V.; classification of Zoöphytes. American Journal of Science, vol. 3 (May): 337-347.]