JDH writes to Sir William Turner Thiselton-Dyer from Castellammare, where he & Lady Hooker have just arrived after spending some time in Rome & Naples. At Naples he visited [Anton] Dohrn's aquarium. He describes some animals of particular interest he saw there: Crinoids, Sepia [cuttlefish], Octopus & Loligo [squid]. He also mentions seeing fish, Ascidia, Corals, Madrepores, Melobesias, Diptera, Beroe, Crustacea, Meduseus & Ulva. In the Naples museum JDH admired the statuary especially a head of Homer & a Venus after Milo. He found the collection of paintings inferior to those at the Vatican & preferred the murals & artefacts from Pompeii, especially: a pane of glass, a surgeon's instrument, a glass plate & a blue glass flagon. JDH has visited Pompeii & tried to understand exactly how it was preserved by the volcanic eruption, he is puzzled why there are not more charcoal remains of the wooden upper stories of buildings & speculates that the town was only partially buried & the exposed material later carried away. Castellammare is where Pliny the elder died during the eruption. JDH is keen to see Herculaneum & understand how its artefacts were not all destroyed by the lava. He also wanted to see Professor Luigi Palmieri at the observatory on Vesuvius but Palmieri is in Rome. JDH intends to ascend Vesuvius the next day. JDH visited the Naples botanical garden but did not see Vincenzo de Cesati or Giuseppe Antonio Pasquale. JDH calls the garden 'wretched' but he did learn something there about Mediterranean Pini. JDH will next go to Amalfi, Salerno & Paestum but not to Capri or Monte St Angelo because of the poor weather. Odoardo Beccari was in Rome appealing against the removal of a herbarium in Florence. JDH comments on the news of Mrs Meade's death & on the poor botanical knowledge of Sir John Lubbock. JDH has asked [John] Smith to give Dyer a list of all RBG Kew garden staff. JDH comments briefly on vegetation in the area, including sour oranges.