My dear Sir

I am sincerely sorry to have given you so much trouble in vain: it was folly in me to doubt for one minute any identification made by one so thoroughly master of the subject, as yourself. There can be no doubt that fig. 6 is a fixed tergum:¹ but what quite misled me was, that this valve has one of its arms or projections quite broken off; and as this broken off arm if whole would have been very visible in the position in which it is figured, I thought it could not be a fixed Tergum. But now I understand all about it, and am very sorry for the trouble I have caused: I hope the specimen will get back safe.

I shall be delighted to receive your work when complete.² I have now finished your MS. and I really cannot too strongly express how excellent your descriptions and Plates appear to me. It is extremely gratifying to me to see how carefully you have studied my work;³ it rewards all the pains, which I have bestowed on the subject.

With every feeling of respect and thankfulness for all your many kindnesses. I remain, in Haste, Dear Sir | Yours very sincerely | C. Darwin.