'These last few days I have had with me Gaskell, whose name you may perhaps know. He is an interesting worker, who has to some extent lately forsaken Physiology to work in morphology (Animal): he labours constantly to work out his idea that the Vertebrata are derived by evolution from the Arthropoda. He regards ammocoets as foreshadowed in Limulus. I think myself that such investigation is too merely speculative at present - but it is admirable to see Gaskell's enthusiasm for the subject he strives upon, & the laborious work he does to lay a foundation for his views.'