Dear Sir

The statement referred to in your favor of the 25^th. inst. was not made by me, perhaps D^r. Perceval Wright F.L.S. was the observer, as I was not present at the Meeting for 1860.¹ If I had any observations or experiments upon the subject I should be delighted to place them at your disposal as I am sure no Naturalist makes a better use of his facts than yourself.

I am grateful to have it in my power to tell you that your valuable ⁠⟨⁠work⁠⟩⁠ on the Origin of Species has done excellent service to Natural Histo⁠⟨⁠ry;⁠⟩⁠ and even to those who are not disposed to agree with you in all your Conclusions relative to transmutation. It has I am happy to say given a great check to species manufacture and induced persons who formerly could see nothing but a new form in every slight variation of structure to reconsider their facts before proposing new sp to our already crowded lists   this I think is a matter of great practical value for at the rate at which we were proceeding in former years nothg but confusion could have been the result. now I find that the good old doctrine I have been endeaving to inculcate for 30 years begins to get a fair hearing, namely that the forms ⁠⟨⁠c⁠⟩⁠alled species appear in all time to have had ⁠⟨⁠cer⁠⟩⁠tain limits of variations which they have ⁠⟨⁠exhi⁠⟩⁠bited under the influence of physical condit⁠⟨⁠ion⁠⟩⁠s and which limits are not the same for every sp. some forms presenting wide deviation from what may be called their typical characters, whilst others move in very limited orbits. I have endeavoured to inculcate this in my Monograph on the Echinodermata and have illustrated it very many examples.²

For some years past I have been studying the Ammonites with the view to publish a Monogr. on them but among them this law of variation is very great indeed so much so that I have not been able to collect materials for more than a very small number of sp. for unless I can obtain an Ammonite in its young, growing, adult and ancient condition I hold that no one is competent to speak of it as a species   this I have been able to do with a few only out of the so called 100^ds. of sp⁠⟨⁠.⁠⟩⁠ contained in the lists³

in much haste believe me always Yours Most truly | Thomas Wright

I expect if I am fortunate in obtaining a sufficient amount of material & make a beginning we shall have fine weeping and waling over “good species” which alas only turn out to be variations of other forms.— I expect my Monogr. on the Oolitic Asteridæ which has been done 8 Mos. and ought to have been out long ago will shew likewise that with a disposition to change there is likewise a law of constancy for you will find in some of the skeletons of the old Starfishes the persistent types of existing structures which have not changed during all that vast period of time which has elapsed between the Liassic and the present period⁴

T. W.