[AD] Many other instances might be added. The hornet clear-wing moth (_Sphecia apiformis_) mimics the hornet or wasp; the narrow-bordered bee-hawk moth (_Sesia bombyliformis_) mimics a bumble-bee. These insects may be seen in the lepidoptera drawers in the Natural History Museum. But perhaps the most wonderful instance of insect-mimicry is that observed by Mr. W. L. Sclater, and given by Mr. E. B. Poulton, in his "Colours of Animals" (p. 252), where a (probably) homopterous insect mimics a leaf-cutting ant, _together with its leafy burden_--a membranous expansion in the mimic closely resembling the piece of leaf carried by the particular kind of ant he resembles. [AE] The late Mr. H. W. Oakley first drew my attention to this snake. Since then Mr. Hammond Tooke has described the facts in _Nature_, vol. xxxiv. p. 547. [AF] _Nature_, vol. xlii. p. 115. [AG] Since the above was written and sent to press, there has been added, at the Natural History Museum, in the basement hall, a case illustrating the adaptation of external colouring to the conditions of life. All the animals, birds, etc., there grouped were collected in the Egyptian desert, whence also the rocks, stones, and sand on which they are placed were brought. Though somewhat crowded, they exemplify protective resemblance very well. [AH] I have to thank Mr. H. A. Francis for drawing my attention to this, and showing me the insects in his cabinet. [AI] "Colours of Animals," p. 73. [AJ] "Origin of Species," p. 161. [AK] "Descent of Man," summary of chap. xvi. pt. ii. [AL] Ibid. chap. xiv. [AM] "Darwinism," p. 108. [AN] Its importance in artificial selection was emphasized by Darwin: "The prevention of free crossing, and the intentional matching of individual animals, are the corner-stones of the breeder's art" ("Animals and Plants under Domestication," ii. 62). [AO] From the absence of interblending in some cases (to be considered shortly), both brown _and_ green forms may be produced; and under certain circumstances, even a power of becoming either brown _or_ green in the presence of appropriate stimuli. [AP] Wallace, "Darwinism," p. 172, where other examples are cited. [AQ] Ibid. pp. 217, _et seq._ [AR] _Journal of the Linnæan Society_, vol. xix. No. 115: "Zoology." [AS] "Animals and Plants under Domestication," p. 145. [AT] Ibid. chap. xvii. [AU] "Darwinism," p. 326. [AV] "Animals and Plants under Domestication," vol. ii. p. 65. For Darwin's general conclusions on hybridism, see vol. ii. p. 162 of the same work.