My dear Jenyns

You will receive two letters together from me, as one was sent to Henslow to take to you, before I received yours this morning.— I really am sincerely grieved to hear the fish give so much trouble.— I beg of you to remember, that I should be very sorry that you should give up time to them, which could better otherwise be spent.— Whatever you may choose to do I shall look at it as clear gain, for otherwise all the specimens would in all probability have been entirely useless & my trouble in collecting them quite lost.— With respect to time, you need not be in any hurry; for all the fossil Mammalia, (& perhaps fossil shells) living Mammalia,—birds, & reptiles have to be completed before the turn for the fish come. Moreover (if funds last out) there will be volume for invertebrate,¹ & the first numbers of this might alternate, with the one or two, or three numbers of fish, just as you choose.— I feel certain before your part is wanted, you will have completed as much as probably would ever be worth your trouble to complete.— For the credit of English zoologists, do not despair and give up; for if you do, then will it be said there was not a person in Great Britain with knowledge sufficient to describe any specimens which may be brought there.— I honestly confess, that without you will do it for this motive, I fear there is none other which will repay you for the stupid task, you have undertaken chiefly out of kindness, I believe, for me.— I am sure I am very much obliged to you,—but I repeat, you must not for a moment hesitate about throwing it up, if your health or want of time prevents your taking any satisfaction in the employment.— You ask me how many species of fish would be published in each number; there would probably be from 12 to 16.— The numbers come out on alternate months, but as I have said, invertebrate animals might alternate with the fish if more than one number is produced.—

I expect to see Eyton in London tomorrow,—when I will give him your fish and a book.—

Believe me, | Most truly yours | Chas. Darwin