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Darwin Correspondence Project

From C. S. Bate   7 April 1868

8, Mulgrave Place, | Plymouth.

Apl 7/68

My dear Sir

The paper on the Dentition of the mole is in the “Transactions of the Odontological society of Gt Britain” for 1867— Until reading your recent work I knew not that you felt an interest in Pathology   I therefore send you a copy of another memoir that I published some time since in the same Society’s Trans—1

While on the Subject of teeth may I ask If in the case of double tooth to which you refer page 2/391 you mean a molar tooth.2 If so I would suggest the following for your consideration— The incisor teeth frequently are developed with a small tubercle behind thus


This is sometimes developed to so large an extent as to form what might be called a double tooth thus


I have seen it quite as much as this last   I am inclined to think that this is the character of tooth your informant meant, which is not uncommon, & to a certain extent is hereditary. The word double by the popular expression for a molar, misleads and as I am inclined to think has misled yourself:— am I right?

Porcelana longicornis } has chelæ unequal in both sexes but larger in males,
" platycheles
" in longicornis much so:
Cancer paposus: equal in female but occasionally unequal in both sexes but most so in males & larger
Enymone aspera— equal in both sexes both much longer & larger in males
Corystes cassivelaunus— equal in both sexes very much longer in males Bells figure is that of a male
Gonoplax bispinosus, equal in both sexes, longer in male.3

The smaller chelæ is larger in males than in females generally, only on the principle that the animal is larger, that is when the chelæ are unequal— If the males & females are of one size & the claws unequal the smaller claw generally resembles that of the female— when the chelæ are right & left equal, & larger, the claw of the males generally differs in form from those of the females.

I think if you wish it, with but little trouble, I could give you a longer list but of course in so doing I should have in some instances to depend upon the authority of others

Believe me yours very sincerely | Yours C. Spence Bate—

P.S | I am now drawing up for the Zoological society the description of what I believe to be a new genus of Prawn— It is a freshwater genus4   The largest that I have is 9 inches long besides the chela which is 10 more— The claws are equal but immensely long & so formed that the nippers cannot be brought to reach the mouth. Strange to say that the species are very close in their resemblance to each other though one comes from the Ganges,—one from Central america, one from Formosa, & one unknown (perhaps Mauritius).5 the repetition of species under similar conditions in various parts of the world is very remarkable

CD annotations

1.1 The paper … tooth. 2.2] ‘Dentition. Sedgwick.’6 added ink
1.1 The paper … right? 2.10] crossed pencil
3.4 Cancer … of others 4.3] crossed pencil
3.12 If the males … females. 3.15] scored blue crayon
6.1 I am … remarkable 6.8] crossed blue crayon
Top of letter: ‘Use | Keep for Dom Animals’ pencil;7 ‘Male larger than ♀ | inequality & size of Chelæ’ blue crayon


Bate sent CD his paper on the dentition of the mole (Bate 1867); CD’s copy is in the Darwin Pamphlet Collection–CUL. Bate may also refer to his paper ‘Pathology of dental caries’ (Bate 1863); no copy has been found in the Darwin Pamphlet Collection–CUL.
See Variation 2: 391.
Porcellana longicornis is now Pisidia longicornis, the long-clawed porcelain crab; Porcellana platycheles is the broad-clawed porcelain crab; Cancer pagurus is the edible crab; Eurynome aspera is the strawberry crab; Corystes cassivelaunus is the masked crab; Goneplax bispinosus is now Goneplax rhomboides, the angular crab (see Ingle 1980, p. 109). Bate also refers to the illustration in T. Bell 1853, p. 159.
Bate refers to his paper ‘On a new genus, with four new species, of freshwater prawns’ (Bate 1868). In Descent 1: 331, CD cited Bate 1868 and referred to the long chelae of these prawns.
In Bate 1868, Bate refers to the species Macrobrachium americanum (the cauque river prawn), M. formosense (the crane river prawn), M. gangeticum (the gangetic prawn), M. africanum (now M. aemulum; see Chace and Bruce 1993, p. 9). Macrobrachium africanum is the species Bate described as from an unknown location.
CD refers to William Sedgwick, who described the case CD cited in Variation 2: 391 (Sedgwick 1863, p. 454).
The reference is to Variation; the passage on the double tooth was not changed in the second edition (Variation 2d ed., 2: 385).


Bate, Charles Spence. 1867. On the dentition in the mole (Talpa Europæa). [Read 1 April 1867.] Transactions of the Odontological Society of Great Britain 5 (1865–7): 261–94.

Bate, Charles Spence. 1868. On a new genus, with four new species, of freshwater prawns. [Read 28 May 1868.] Proceedings of the Zoological Society of London (1868): 363–8.

Bell, Thomas. 1853. A history of the British stalk-eyed crustacea. London: John Van Voorst.

Descent: The descent of man, and selection in relation to sex. By Charles Darwin. 2 vols. London: John Murray. 1871.

Ingle, Ray W. 1980. British crabs. London: British Museum.

Sedgwick, William. 1863. On the influence of sex in hereditary disease. British and Foreign Medico-Chirurgical Review n.s. 31: 445–78; 32: 159–97.

Variation 2d ed.: The variation of animals and plants under domestication. By Charles Darwin. 2d edition. 2 vols. London: John Murray. 1875.

Variation: The variation of animals and plants under domestication. By Charles Darwin. 2 vols. London: John Murray. 1868.


On dentition of moles. On double teeth [see Variation 2: 391].

Difference in size of male and female Crustacea.

Letter details

Letter no.
Charles Spence Bate
Charles Robert Darwin
Sent from
Source of text
DAR 82: A67–8
Physical description
4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6101,” accessed on 21 September 2021,

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