Barnacles
A single barnacle species was left to describe, and on 1 October 1846 Darwin began a paper on it, working on dissecting with the assistance of Hooker who was now at Kew. To compare this with other species he borrowed specimens, and soon became involved in a much needed comprehensive study of these peculiar creatures that had recently been found to be crustaceans rather than molluscs. To Hooker such an exhaustive study might dampen Darwin's tendency to speculative theorising, and to Darwin it would establish his credentials.
Read more about this topic: Development Of Darwin's Theory