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Darwin Correspondence Project

From T. V. Wollaston   [early November 1856]1

Scarites (a genus of the Carabidæ), there also the mandibles are greatly developed (in proportion, almost as much as in the Lucanidæ), & in size eminently variable.2

And, as I suppose the principle is the same whether the organs be above or below the medium standard of development, we might perhaps cite the wing-cases (elytra) of Melöe as a case in point. These are unusually reduced in dimensions (for the Coleopterous type), scarcely covering two-thirds of the abdomen; & they are, in some of the species, very inconstant in size.—

The connateness of elytra (as having merely a character, & not an organ) will not perhaps suit you.— otherwise I might mention that the only Harpalus (I believe) on record in which the wing-cases are ever joined is the H. vividus of the Madeiran Islands (opus diab. p.p. 56, 57);3 but that character (anomalous as it is) does not always occur in that species,—the elytra being sometimes connected, sometimes sub-connected, & occasionally almost (if not entirely) free.—4

Such are a few facts which strike me primâ facie, from very ordinary & commonplace material. With the extravagancies of Nature (such as the tropics may produce) I have nothing to do; but, if this principle be an universal one, an examination of the Leaf-insects & (for instance) those remarkable Homopterous creatures in which the thoracic projections take every conceivable form, might perhaps throw some additional light upon it.—

The basal joint of the feet of some of the Madeiran Tarphii is wonderfully developed into an elongated spine; but I have not yet observed any variability in this,—unless indeed (as is not likely) I have been mistaken in regarding it as sexual.

I must however cease, for Time fails, & moreover I am not in great condition for either thought or work. Good luck to the Helices: may they live,—tho’ not, I trust, in salt-water.5

Yours very sincerely | T V Wollaston.

CD annotations

1.1 Scarites … variable. 1.2] crossed pencil; ‘Q’6 added pencil, circled pencil
2.1 And … principle] ‘10’7 added brown crayon
‘whole genus. rudimentary organ’added pencil
crossed pencil; ‘Q’8 added pencil, circled pencil
double scored pencil
crossed pencil

Footnotes

Dated by the reference at the end of the letter to the land snails that Wollaston had given to CD. CD recorded his first experiments on Wollaston’s Porto Santo snails in his Experimental book, p. 17 (DAR 157a) on 30 November 1856.
CD had apparently requested further details concerning cases mentioned in chapter 4, ‘Organs and characters of variation’, of Wollaston 1856.
The ‘opus diab[olicus]’ is Wollaston 1854.
The tendency of the wing-cases in Harpalus to be joined was discussed in Wollaston 1856, pp. 96–7, and Natural selection, pp. 124–5, 313.
Wollaston had given CD a bag of live molluscs he had collected on Porto Santo, Madeira to be used in CD’s experiments to test their ability to withstand the effects of sea-water. Land molluscs presented a considerable challenge, through their ubiquitous presence on oceanic islands, to CD’s views on the dispersal of seeds and ova by sea transport. Wollaston was a primary advocate of the land-bridge theory of geographical distribution. See letter from T. V. Wollaston, [11 or 18 December 1856].
The ‘Q’ stands for quoted. CD used this information from Wollaston in Natural selection, p. 313.
The number of CD’s portfolio on abortive organs.
This information was quoted in Natural selection, p. 313.

Summary

Variability of certain features within insect genera.

Letter details

Letter no.
DCP-LETT-2030
From
Thomas Vernon Wollaston
To
Charles Robert Darwin
Sent from
unstated
Source of text
DAR 181: 138
Physical description
4pp inc †

Please cite as

Darwin Correspondence Project, “Letter no. 2030,” accessed on 15 September 2019, https://www.darwinproject.ac.uk/letter/DCP-LETT-2030.xml

Also published in The Correspondence of Charles Darwin, vol. 6

letter