Note 1 — Chapter XXV · LAWS OF VARIATION, continued.—CORRELATED VARIABILITY.
Reading edition
‘Hist. des Anomalies,’ tom. iii. p. 392. Prof. Huxley applies the same principle in accounting for the remarkable, though normal, differences in the arrangement of the nervous system in the Mollusca, in his paper on the Morphology of the Cephalous Mollusca in ‘Phil. Transact.,’ 1853, p. 56.