In Hooker's lecture he gives St.Dabeoc's Heath and Calluna vulgaris as the most striking of the few boreal plants in the Azores.

Darwin seems to have been impressed by the boreal character of the Azores, thus taking the opposite view to that of Sir Joseph.

See Letter 370, note.) I thought the Azores flora was more boreal, but what can you mean by saying that the Azores are nearer to Britain and Newfoundland than to Madeira ?--on the globe they are nearly twice as far off.

(366/3.

See Letter 368.) With respect to sea currents, I formerly made enquiries at Madeira, but cannot now give you the results; but I remember that the facts were different from what is generally stated: I think that a ship wrecked on the Canary Islands was thrown up on the coast of Madeira.
You speak as if only land-shells differed in Madeira and Porto Santo: does my memory deceive me that there is a host of representative insects?
When you exorcise at Nottingham occasional means of transport, be honest, and admit how little is known on the subject.