Volume Ii Part 3 (1/2)

I have not Baer's papers; but, as far as I remember, the subject is not fully discussed by him.

I quite agree about Wallace's position on the ocean and continent question.

To return to geographical distribution: As far as I know, no one ever discussed the meaning of the relation between representative species before I did, and, as I suppose, Wallace did in his paper before the Linnean Society. Von Buch's is the nearest approach to such discussion known to me.

LETTER 400. TO W.D. CRICK.

(400/1. The following letters are interesting not only for their own sake, but because they tell the history of the last of Mr. Darwin's publications--his letter to ”Nature” on the ”Dispersal of Freshwater Bivalves,” April 6th, 1882.)

Down, February 21st, 1882.

Your fact is an interesting one, and I am very much obliged to you for communicating it to me. You speak a little doubtfully about the name of the sh.e.l.l, and it would be indispensable to have this ascertained with certainty. Do you know any good conchologist in Northampton who could name it? If so I should be obliged if you would inform me of the result.

Also the length and breadth of the sh.e.l.l, and how much of leg (which leg?) of the Dytiscus [a large water-beetle] has been caught. If you cannot get the sh.e.l.l named I could take it to the British Museum when I next go to London; but this probably will not occur for about six weeks, and you may object to lend the specimen for so long a time.

I am inclined to think that the case would be worth communicating to ”Nature.”

P.S.--I suppose that the animal in the sh.e.l.l must have been alive when the Dytiscus was captured, otherwise the adductor muscle of the sh.e.l.l would have relaxed and the sh.e.l.l dropped off.

LETTER 401. TO W.D. CRICK. Down, February 25th, 1882.

I am much obliged for your clear and distinct answers to my questions.

I am sorry to trouble you, but there is one point which I do not fully understand. Did the sh.e.l.l remain attached to the beetle's leg from the 18th to the 23rd, and was the beetle kept during this time in the air?

Do I understand rightly that after the sh.e.l.l had dropped off, both being in water, that the beetle's antenna was again temporarily caught by the sh.e.l.l?

I presume that I may keep the specimen till I go to London, which will be about the middle of next month.

I have placed the sh.e.l.l in fresh-water, to see if the valve will open, and whether it is still alive, for this seems to me a very interesting point. As the wretched beetle was still feebly alive, I have put it in a bottle with chopped laurel leaves, that it may die an easy and quicker death. I hope that I shall meet with your approval in doing so.

One of my sons tells me that on the coast of N. Wales the bare fis.h.i.+ng hooks often bring up young mussels which have seized hold of the points; but I must make further enquiries on this head.

LETTER 402. TO W.D. CRICK. Down, March 23rd, 1882.

I have had a most unfortunate and extraordinary accident with your sh.e.l.l. I sent it by post in a strong box to Mr. Gwyn Jeffreys to be named, and heard two days afterwards that he had started for Italy.

I then wrote to the servant in charge of his house to open the parcel (within which was a cover stamped and directed to myself) and return it to me. This servant, I suppose, opened the box and dropped the gla.s.s tube on a stone floor, and perhaps put his foot on it, for the tube and sh.e.l.l were broken into quite small fragments. These were returned to me with no explanation, the box being quite uninjured. I suppose you would not care for the fragments to be returned or the Dytiscus; but if you wish for them they shall be returned. I am very sorry, but it has not been my fault.

It seems to me almost useless to send the fragments of the sh.e.l.l to the British Museum to be named, more especially as the umbo has been lost.

It is many years since I have looked at a fresh-water sh.e.l.l, but I should have said that the sh.e.l.l was Cyclas cornea. (402/1. It was Cyclas cornea.) Is Sphaenium corneum a synonym of Cyclas? Perhaps you could tell by looking to Mr. G. Jeffreys' book. If so, may we venture to call it so, or shall I put an (?) to the name?

As soon as I hear from you I will send my letter to ”Nature.” Do you take in ”Nature,” or shall I send you a copy?

CHAPTER 2.VIII.--MAN.

I. Descent of Man.--II. s.e.xual Selection.--III. Expression of the Emotions.

2.VIII.I. DESCENT OF MAN, 1860-1882.

LETTER 403. TO C. LYELL. Down, April 27th [1860].