My dear Sir

I have received your very kind note of yesterdays date, & beg to say in reply to your first question, that in “typical” I have very probably made use of a wrong word— the forms I allude to are such as Buccinum undatum, & allied species (B. Ciliare, B Humphreysianum, B. Cyaneum, B. Fusiforme &c.)— Fusus Antiquus, F Icelandicus, F propinquus &c.— The Genus Trichotropis—subgenus Margarita— Purpura lapillus— & among bivalves Cyprina Islandica—& the genera Saxicava, Astarte, Leda, Yoldia, Crenella &c.— which are principally develloped in the Arctic Seas, & are considered to be characteristic of these, as the larger Cyprææ, Conus, Voluta, Mitra &c. of the tropical regions.¹

With respect to your second question² I have to state that it has never been my lot to fall in with drift timber—other than what had been used in the construction of vessels, either at sea or upon the Coasts of Britain, though I give no opinion against the statements of its being occasionally washed ashore upon the Coasts of Ireland & of the Western Hebrides—which indeed appears to me highly probable—

I never heard of vessels at sea striking against floating timber other than wreck—& I do not believe that timber ever floats under the surface, though it will after a long time, get saturated with water & sink to the bottom, where if not in too great a depth, it eventually gets destroyed by the Teredo, Xylophaga—Pholades &c.

It will at all times afford me the greatest pleasure to be enabled in any way to assist you in your researches—though my ability for it can be but small—

Believe me always | My dear Sir | Yours most truly | Rob^t. M^c.Andrew Cha^s. Darwin Esq^r.