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Darwin Correspondence Project

From James Murphy   10 May 1876

The Infirmary | Sunderland

Dear Sir

Having just read yr. “Descent of Man” with so much pleasure I trust you will excuse the liberty I take in mentioning two points which may have escaped yr. notice.

The first is under the head of “Rudiments”.1

Marshall has described (“On the development of Man & Mammalia” Philosoph. Trans. 1850) “a vestgial fold of the pericardium which is a vestige of a left superior vena cava that exists in early embryonic life” and also in the Elephant the Edentata & the Rodents.2

The second point may seem far-fetched but it is this.

The Uterus in woman points downwards & backwards. Now when man went on all fours and the penis was without a frænum—as most of the Mammalia) copulation took place vis-a-dos but when man became erect and copulation took place vis-a-vis it was necessary to have a fraenum to direct the meatus of the penis backwards, towards the mouth of the womb.3

Respectfully submitting those points to yr. notice & trusting you will excuse the liberty I have taken in doing so | I am | Faithfully yours | James Murphy



Descent 2d ed., pp. 11–25.
John Marshall’s description occurs in Marshall 1849; however, Marshall refers to ‘Marsupials and some other Mammalia’ (J. Marshall 1849, p. 160), not Edentata (a former order comprised of armadillos, anteaters, and sloths).
The fraenum or frenulum is a membrane that connects the foreskin to the shaft of the penis; the meatus is the opening of the glans at the head of the penis.


Descent 2d ed.: The descent of man, and selection in relation to sex. By Charles Darwin. 2d edition. London: John Murray. 1874.

Marshall, John. 1849. On the development of the great anterior veins in man and mammalia; including an account of certain remnants of foetal structure found in the adult, a comparative view of these great veins in the different mammalia, and an analysis of their occasional peculiarities in the human subject. [Read 21 June 1849.] Philosophical Transactions of the Royal Society of London 140 (1850): 133–70.


A reader of Descent offers two items: 1. Masters observed a pericardial fold in humans and other mammals which is a vestigial left superior vena cava;

2. JM suggests the frenum of the human penis became necessary for vis-à-vis copulation when man became bipedal.

Letter details

Letter no.
James Murphy
Charles Robert Darwin
Sent from
The Infirmary, Sunderland
Source of text
DAR 171: 323
Physical description
ALS 3pp

Please cite as

Darwin Correspondence Project, “Letter no. 10503,” accessed on 1 October 2023,

Also published in The Correspondence of Charles Darwin, vol. 24