Ice could not have formed the blockages in Lochaber unless in every case the water escaped over some col into a contiguous valley on the same watershed, or into the eastern watershed. Supposes that the cols were not land-straits, but the places where the lakes were drained when forced to flow the wrong way.

Sends a preliminary reply to CD’s query [5890]. Ten males to one female among captured micro-Lepidoptera. Six females to four or five males in those he has bred. HTS is aware this is diametrically opposed to information from [Alexander] Wallace and Bates, but the true proportion of sexes can only be ascertained by breeding.

Replies to CD on proportion of sexes in butterflies, coloration of moths, and courtship. Encloses copies of letters on these subjects between HTS, Henry Doubleday, and John Hellins.

Protective coloration in butterflies.

[Alexander] Wallace’s suggestion that collecting larger larvae of females accounts for error in counting proportion of sexes.