RT has sent his observations on orchids to CD. Has found only one case of an insect with a pollinium adhering to it.

Thanks CD for two letters and his portrait.

CD’s book [Orchids] opened up terra incognita for him.

His work on S. African butterflies continues.

Reports on a moth that punctures peach skins.

Interesting that thoughtful naturalists are forced to admit mutability of species.

Some notes on Oxalis.

Comments on CD’s paper on Linum [Collected papers 2: 93–105].

Sends specimens of dimorphic and trimorphic Oxalis.

Comments on H. W. Bates’s work [Naturalist on the river Amazons].

Butterflies of Mauritius.

RT’s Bonatea paper published by Linnean Society [J. Linn. Soc. Lond. (Bot.) 9 (1867): 156–60].

On ocelli.

Sexual differences and proportion of sexes in butterflies.

Coleoptera.

[See Descent 1: 310; 2: 132.]

Variations in the ocelli of Lepidoptera.

Encloses six pages from his catalogue of S. African butterflies [Rhopalocera Africae australis, 2 pts (1862, 1866)].

Sends prospectus of forthcoming work by his brother [Henry Trimen] and W. T. Thiselton-Dyer [Flora of Middlesex (1869)]. Hopes CD will subscribe.

Proportion of sexes in butterflies; discussion of subject at meeting of Entomological Society, London.

Attraction of males by female Lasiocampa quercus. [see Descent 1: 311–12.]

On attraction of males by females in moths. H. T. Stainton mentions a case.

Coloration in moths.

Quotes Achille Guénée on relative proportion of sexes in Phalaenites.

Approves CD’s revision on coloration of moths.

Impressed with apparent adverse tendencies: one toward sexual selection, the other toward protection.

Extract from Émile Blanchard’s Metamorphoses, moeurs et instincts des insectes [1868], on attraction of males by female Lepidoptera, and possible explanation.

Thanks CD for his orchid paper ["Fertilization of orchids", Collected papers 2: 138–56]. Comments briefly on orchids.

Discusses moths in which the wing underside is the most brightly coloured, and relates his observations on sexual selection by a moth, Syntomis.

Thanks RT for his letter and MS.

Is astonished by the different forms of orchids he describes.

Urges RT to describe and experiment with two or three of the more distinct genera.

"I believe, or am inclined to believe in one or very few primordial forms, from community of structure and early embryonic resemblances in each great class."

Further discusses RT’s observations on Cape [of Good Hope] orchids and asks whether it would be possible for him to send some specimens to Kew.

CD has drawn up a paper from RT’s orchid notes on the fertilisation of Disa grandiflora for the Linnean Society [J. Linn. Soc. Lond. (Bot.) 7 (1863): 144–7].

CD would welcome seeds of any Cape Oxalis for his investigation of dimorphism.

Discusses methods of pollination in orchids.

Thinks RT should investigate Physianthus to see if it requires insect aid for fertilisation as the Asclepiadaceae do.

CD’s doctor [J. M. Gully] has ordered him to do nothing for six months.

Thanks RT for orchid specimen.

Dares not look at Oxalis flowers.

Regrets RT cannot get seed, especially from his trimorphic flowers.

Asks for bulbs of two or three forms.

Oxalis plants have arrived safely [see 4347].

CD regrets his mistake about Disa; will correct it.

Thanks RT for his additional facts about Disa.

Is recovering slowly from ten months’ illness.

Asks whether Strelitzia reginae grows in gardens at the Cape. Suspects it must be fertilised by a bird.

Has forwarded RT’s paper on Bonatea to the Linnean Society [J. Linn. Soc. Lond. (Bot.) 9 (1865): 156–60].

The Oxalis sent by RT flowered but CD has made out only two forms; he thinks there ought to be three, so would welcome more seed.