skip to content

Darwin Correspondence Project

From Edward Blyth   5 April 1868

7 Princess Terrace,

April 5/68.

Dear Mr. Darwin,

I am not aware that the fact of occasional syndactylism in man has ever been published. I learned it from Bartlett, who assures me that it is not uncommon, and, as I before mentioned, one of the Keepers at the Z. G. has this peculiarity. It is the 2d. & 3d. toes of the foot that are joined, as also in Hylobates.1 Certainly, I never remarked an instance among the myriads of naked feet that I have seen in India, and it would be more noticeable in people who have never cramped their feet by wearing shoes, inasmuch as their toes are straight and flexible, finger-like, and spreading. I remember being much struck with the appearance of the natural human foot when first I observed it, & I did think of procuring specimens from the dissecting rooms to send in spirit to the Col. Surg. Museum.2 In Hindu and Egyptian Sculpture the straight and finger-like toes—the foot-fingers—are represented, not so in the Greek statues. I have several times observed in the naked feet of sailors an abnormity in which the great toe exhibits a very strong tendency to be opposed to the other toes


the joint projecting much at a. Of these I have seen at least 12 doz instances. There were two sailors (not related) thus characterized on board the ship in which I went to India—3

In the marsh terns (Hydrochelidon) & in the Sterna melanogaster, the seasonal change of colour is common to the two sexes; ditto with the black cap assumed in spring by most terns, & the hood of the hooded gulls.4 In Gallicrex cristatus, the frontal shield is small and pointed in winter,


but at the breeding season it rises into a caruncle thus,


being of a red colour, and at this time the males are very pugnacious, and are kept for fighting by the inhabitants of Eastern Bengal, who designate the bird the Kora. As it is one-third larger than its female, I think there can be little doubt of its being polygamous.5

The wing-plumes of the male ostrich are unquestionably much more developed than those of the female; but whether both sexes of woodpeckers incubate is more than I can tell.6 In the touracos, toucans, and barbets, there is no sexual diversity of plumage; in the trogons there is. In some hornbills also, & there is generally some difference in the colouring of the casque, and of the iris, & also any naked skin; thus in Bucorax abyssinicus the gular pouch of ♂ is bright red, in ♀ leaden-blue.7 Rollers,8 bee-eaters, & kingfishers have mostly the sexes alike, but in Ceryle rudis the ♂ only has the second black pectoral bar.9 Swainson imagined that the latter indicated a different species, & styled the ♂ Ispida bitorquata!10

Yours truly, | E Blyth.

CD annotations

1.1 I am … India— 1.17] crossed pencil
2.1 In … gulls. 2.3] crossed dotted line, ink; ‘Terns’ pencil
2.1 In … Kora. 2.7] crossed blue crayon; ‘Blyth April 8— 68—’ in margin blue crayon
2.3 In Gallicrex … polygamous. 2.9] crossed ink
3.1 The … female; 3.2] scored blue crayon; ‘♀ Bird’ blue crayon
3.2 but … tell. 3.3] del pencil
3.3 touracos] underl blue crayon
3.3toucans] underl blue crayon; underl pencil; circled red crayon
3.3 barbets] underl blue crayon; circled red crayon
3.3 touracos … barbets,] ‘In Gould’s Book Trogons or Toucans11 pencil


CD had asked Blyth for a reference to syndactylism in humans in his letter of 4 April [1868]. Blyth refers to Abraham Dee Bartlett and to a keeper at the Zoological Gardens, Regent’s Park, London, who has not been identified. Blyth may have mentioned the keeper at the Zoological Gardens when he met CD in London on 24 March (see letter to Roland Trimen, [21 March 1868]).
Blyth refers to the Hunterian Museum of the Royal College of Surgeons.
Blyth went to India in September 1841 (ODNB).
The genus Hydrochelidon is now Childonias, family Sternidae; Sterna melanogaster, the black-bellied tern, is now S. acuticauda. A number of species in the genus Larus are described as ‘hooded gulls’; they are characterised by the darker colour of head plumage, particularly during the breeding season.
In Descent 2: 41, CD cited Blyth on the size difference in Gallicrex cristatus (now G. cinerea, the watercock). CD mentioned the development of the red caruncle, but did not cite Blyth for the information (Descent 2: 80).
Blyth refers to Bucorvus abyssinicus, the Abyssinian ground hornbill.
Rollers (family Coraciidae) belong to the order Coraciiformes, which also includes bee-eaters and kingfishers.
Ceryle rudis is the pied kingfisher.
Blyth refers to William Swainson and to Swainson 1836–7, 2: 336, where Swainson listed both Ispida bitorquata and I. torquata.
CD refers to John Gould’s monographs on the Ramphastidae (toucans) and Trogonidae (trogons; J. Gould 1834 and 1838). Gould noted that true toucans displayed no sexual differences in the colour of their plumage (J. Gould 1834, p. 2). He observed that trogons differed in their plumage according to both sex and maturity (J. Gould 1838, p. v).


Discusses the human foot and its abnormalities; notes an example of syndactylism.

Gives his observations on sexual differences in coloration of terns and ostriches.

Letter details

Letter no.
Edward Blyth
Charles Robert Darwin
Sent from
London, Princess Terrace, 7
Source of text
DAR 84.1: 136, DAR 160: 213
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6094,” accessed on 24 June 2017,

Also published in The Correspondence of Charles Darwin, vol. 16