Dear Forbes

I am extremely obliged for your information on depths: I fear I shall not be able to give the additional data, which you require. Should I hereafter be able to do so, I will apply to you again.¹

I am very glad you have so soon found a naturalist for the Californian expedition I presume M^r Edmonstone² is actually appointed; otherwise I was going to have suggested D^r Dieffenbach, who travelled in New Zealand & who, I have little doubt, would have gladly gone.³

I do not at all know the route of the expedition, either outwards or homewards otherwise I would gladly make any suggestions which might occur to me on points worthy of observation. Have you, or do you know those who have, any power in settling any point, where the ship might call; for I have little doubt that Cocos isl^d., north of the Galapagos Archipelago, from its insulated position, & judging from the Galapagos Arch. would have a most peculiar flora & fauna.

The Revillagego (I forget how to spell it) group⁴ off the coast of Mexico, I believe, has never been visited by a Naturalist. Suggest to M^r Edmonstone to take a good stock of small steel rat-traps, with which he can easily take many rodents.

I can think of only one special point of geological interest on the NW. & Californian, coast viz to ascertain in what latitude southward great angular erratic boulders have been transported by floating ice over plains or across wide valleys; this point w^d be very interesting, in comparison with the southern limit of boulders in the United States.

Of course M^r Edmonstone will attend to all facts relating to the elevation of the land,—a class of phenomena so grandly displayed in southern America.

If M^r Edmonstone liked to take the trouble of informing me, of the route of the Ship outwards & homewards, I daresay, I c^d suggest a few points for his observation.

Will he visit the Pacific coral-isl^ds.; if so I hope he will apply to the Admiralty for my Coral-Volume.

I have had a circular from the Ray Society⁵ & I do not know to whom to pay my guinea: I shall be up next council & perhaps you will then inform me.

With many thanks for your information | Believe me | Ever yours sincerely | C. Darwin

Will M^r Edmonstone come home round the world, there is some most interesting pure geology to be done at the Mauritius.—