Louis Agassiz, Contributions to the Natural History of the United States of America, 1860.

Agassiz’s only major scientific (as opposed to popular) work published during the second, American phase of his career. “The great defect in Darwin’s treatment of the subject of species,” writes Agassiz, “lies in the total absence of any statement respecting the features that constitute individuality.” The spectacular lithograph of the Cyanea arctica, the largest known American species of jellyfish, prepared by Agassiz’s master draftsman Antoine Sonrel, reflects Agassiz’s interest in visual representation but also in the concept of individuality which he felt Darwin had inadequately understood. The Cyanea, its long tentacles spilling beyond the frames of the illustration, demonstrates such individuality in particularly striking fashion.