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Darwin Correspondence Project

From J. G. Malcolmson   30 November 1839


Novr 30th. 1839

My Dear Sir,

I take advantage of a young friend going to London to send you a specimen of a coralline, which I obtained from a reef of rocks extending from the little island of “Sowna” into the Pentland frith. It lived, along with actinia and many other animals, in a hollow in the bituminous rocks of that region. I was surprised to see the shore of the south east of Hoy covered with vast quantities of white sand and gravel—not as usual composed of shells but of ramose corals. My interest in this specimen, however, is of a different kind. The oysters of our raised beaches are marked by serpentine depressions such as you see on the base of the coralline;—and the limestones both of the Lias and old red Sandstone at Cromarty, are similarly marked, when washed ashore. Dr. Fleming1 had been interested in this, when at Cromarty some time before, but could not find out the origin of the grooves: In breaking up some of the argillaceous limestone shale of the old red sandstone in 1837, at extreme low water mark, I found them to be marked in the same way, and I found each groove, or rather canal to contain a nereis of corresponding size, and satisfied myself that this feeble creature had bored an habitation for itself. Dr Fleming, to whom I sent some specimens, would not admit this—and Miller2 hesitated (till he saw the coral). Dr. Fleming seemed to think it assuredly an ancient borer, and referred to similar markings on the surface of the chalk under the London clay, as giving additional interest to the subject. I was therefore well pleased to find these recent corallines everywhere bored in the same way, both where they adhered to the smooth flagstone, and through their mass. Numerous other borers preyed on this newly formed limestone at the same time. Each canal contained a larger or smaller nereis according to its size and they had a relation to each other that could not have existed, had the worm only used the holes of another creature. Dr. Fleming says that they only bore clay and submarine peat—but I see no reason why they, as well as some of the more delicate and smooth shells, should not penetrate limestone. I have sent some of the worms to Dr Johnston of Berwick;3 and as you are engaged on corals think you may like to have a specimen so marked.

I find I was right at first in my understanding of Allan’s account of Aldabra— he is positive that the island is of coral vitrified or silicified. Recollect that Mr Lonsdale even, at first, took the corals from Shahar in arabia for trap. Allan promised to write you a long letter and I gave him your journal to read for the purpose of his adding some remarks regarding it— I hope to get his letter soon—but he is in great demand and being young, more close attention is expected from him, than would be requisite had he been longer here. The subject is also painful to him, from his never to be repaired loss. He is positive about the Comoros. If you could send him the loan of Owen’s4 (of whom he has not a high opinion) or some other chart he would insert remarks on all the places he visited, and many of which he surveyed.〉 It would be returned to you. My brother 9 King William Street will take care of it.

I had intended to have said something of sheepdogs but I have not time. I could send you a few small specimens of “Kunkar” and of “Laterite” our two Indian puzzles, if they could be of use to you for the purpose of comparison. We have added an important new locality of the lower fossils on the Bogie river near Huntly, in Aberdeenshire. I have not yet been there.

Yours truly J G Malcolmson

I have asked allan to write down his very important experiments on the growth of coral. 3 feet in 6 months! think of that

Please to send the packet to Royle over from the Geol. anytime you are there


John Fleming.
Hugh Miller.
George Johnston.
Allan: James Brands Allan. Owen: William Fitzwilliam Owen. See Coral reefs, p. 62 n.


Sends specimens of coralline with vermiform holes.

J. Allan’s observations of Aldabra and the Cormoros [see Coral reefs, p. 186] and news of his experiments on the growth of coral.

Letter details

Letter no.
John Grant Malcolmson
Charles Robert Darwin
Sent from
Source of text
DAR 39: 15–17
Physical description
5pp †

Please cite as

Darwin Correspondence Project, “Letter no. 548,” accessed on 4 August 2021,

Also published in The Correspondence of Charles Darwin, vol. 2