Thanks CC for two memoirs [see 6575. The other was possibly "Die Cypris-ähnliche Larve der Cirripedien", Schr. Ges. Beförd Naturw. Marburg (1869)].
Haeckel is too enthusiastic and too bold in drawing conclusions.
CD sees no reason to add to what he says on isolation, in new edition of Origin.
Lists specimens he has available for CC’s intended study of metamorphoses of Lepas.