My dear Forbes

I have read with much interest, M^r Bate’s paper & admired his beautiful & excellent drawings—² I am sorry to say that M^r. Bates is not at all aware (as he suggests himself) how much has been published on the Cirripedia— I presume he would consider that the Chief Point in his paper is the fact that the metamorphosis commences under a quite different form (viz a six-legged little crustacean) compared with the last form described by V. Thompson;³ it must no doubt have been a great satisfaction to him having made out this important fact independently But Burmeister in his Beitrage zur an Rankenfüsse has published figures (poor) & detailed description of the whole series of similar changes in the larva of Anatifa⁴

And Goodsir in the Edin New. Phil. Journal. has done the same thing for Balanus—⁵ Goodsir’s figures of the first & second (not the last) stages are closely similar, but not identical with those of M^r Bates.— M^r B. does not seem aware of V. Thompson’s second Paper in Royal Soc Transt. on the first (N.B. V. Thompson did not even conjecture there were two stages) stage of the larva of Anatifa;⁶ for he gives a copy of Thompsons figure copied by Prof^r. Harvey of Dublin (not Captⁿ!) in his sea side book.—⁷ I will give some other authorities not known to M^r Bates, who speaks of the mature Cirripedes not having eyes, which shows he has not heard of Prof^r. Leidy’s discovery⁸ which I have repeatedly verified having found optic nerve & ganglion &c.— Kölliker has figured the spermatozoa of Cirripedia,⁹ but as far as I have seen M^r Bates figures seem more accurate, than Kölliker, & yet I hardly like to distrust on such a subject such an observer.¹⁰

When M^r Bates speaks of the pulp (an inappropriate name I think) in the tubes of shell of Balanus being isolated, I conceive he is mistaken, as he would see if he read D^r. Coldstream’s paper in Encycp. of Anatomy—¹¹ But the most valuable & extensive paper unknown to M^r Bates is by Martin S^t Ange read 16 years ago to the Acad: Sc: Paris, with excellent figures;¹² if M^r Bates had read this he would have seen that his figure Tab. V. is very erroneous; I can assure him I have repeatedly verified S^t Ange’s observations; M^r B. makes the two so called testes (really vesiculæ seminales, the testes being quite distinct) debouch at the anus! & the alimentary canal debouch at the end of the probosciformed male organ or penis! My unpublished observations are of course of no authority but I see many points very different from M^r Bates, & it would be unfriendly not to caution him that his description of the female parts of generation are very far, as I believe from the truth.—¹³ Indeed S^t Ange would show this in two leading points & S^t Ange has been confirmed by Rudolph Wagner¹⁴ and Lovèn¹⁵ in parts of his description—

I do not know whether M^r Bates will think my advice uncalled for,¹⁶ but I would recommend him to publish only his observations on the larva out of Justice sake, alluding to Burmeister, &, Goodsir’s previous discovery of the great fact of the complex metamorphosis of the Cirripedia— Perhaps he had better look at Goodsir’s figures (Edin: New. Phil. Journal. July 1843) & see how near his are, & allude to points of difference, some of which I consider of very considerable interest I will add that letters of reference to each corresponding part would make his figures plainer in Tab I.— If I might venture to beg a favour it would be, when M^r Bates paper is published, if he would give me (supposing he has such) two or three specimens of the larva in the 2^nd & 3^rd stage as figured in Tab I. I should like to see rather a fuller description of the curious point on the basal segments of the legs, which Goodsir imperfectly figures—¹⁷ Would M^r Bates permit me in my introduction to my systematic volume to be published this autumn in which I shall give an abstract of my anatomical observations, to allude to his drawings of the early stages of the larva?¹⁸ One word more, would it not be advisable for M^r Bates to give some measurements of the embryo figured 18–19, for they must be excessively minute—¹⁹ The fact of the 21 segments being reckonable is exceedingly curious— Forgive this long letter, but I did not like to say simply—that parts of M^r Bates work had been forestalled without going into details—

Believe me dear Forbes with sincere thanks for your kind expressions about our bitter loss.²⁰

Yours most truly. | C. Darwin.