_Male_: resembles _O. Criton_ in the form and extent of the yellow patch, but the upper wings differ in having the outer half of a lighter tint; on the under surface this outer half of the wing is of a light ash-colour. Abdomen almost wholly black beneath. No red patches at the base of the wings, or any red collar. _Female_ unknown. _Hab._ Timor (_Wall._). This is a very distinct species, though at first sight resembling several others. I obtained a single male specimen only. 14. ORNITHOPTERA HALIPHRON, Boisduval. _O. Haliphron_, Bd. Sp. Gén. Lép. p. 181 (♂); Felder, Lep. Fragm. p. 37, Taf. ii. f. 2, 3 (♂, ♀). _Hab._ Macassar (Celebes) (_Wall._). 15. ORNITHOPTERA AMPHRISIUS, Cramer. _P. Amphrisius_, Cr. Pap. Ex. t. 219. f. A; Godardt, Enc. Méth. ix. p. 27, pt. _O. Amphrisius_, Bd. Sp. Gén. Lép. p. 178. _Hab._ Malacca, Java, Borneo (_Wall._). This may be readily distinguished from the allied species by the upper wings in the male being yellow-marked, and by the absence of red spots at the base of the wings beneath in both sexes. c. _Brookeana_ group. 16. ORNITHOPTERA BROOKEANA, Wallace. _O. Brookeana_, Wall. Proc. Ent. Soc. 1855, p. 104; Hewitson, Ex. Butt. Papilionidæ, i. f. 1. _Papilio Trogon_, V. Voll. Tijdschrift voor Ent. 1860, p. 69, pl. 6. _Hab._ Borneo (Sarawak) (_Wall._), Sumatra (_Leyden Museum_). _Remarks._—I have been in much doubt about the position of this remarkable species, and was for some time inclined to place it among the Papilios. It agrees, however, far better with _Ornithoptera_ in the form and stoutness of the wings, the long stout and curved antennæ, the red collar and patches at the base of the wings beneath, the abdominal fold, and the flight and general appearance. It is powerful on the wing, and occasionally settles on the ground in damp sunny places. It inhabits the interior of North-west Borneo and the mountains of West Sumatra. The female is unknown. It is peculiar in the great length of the discoidal cell of the wings and its altogether unique style of coloration, and must be considered as the type of a distinct group of the genus _Ornithoptera_. PAPILIO. This is without doubt the finest and most remarkable genus of Diurnal Lepidoptera. About 360 species are now known, all, except ten, being tropical or subtropical. I have given at p. 23 the characters of the sections and groups into which I divide the Malayan species. SECTION A. a. _Nox_ group. 17. PAPILIO NOX, Swainson. _P. Nox._, Sw. Zool. Ill. pl. 102; Horsf. Lep. Ins. E. I. C. pl. 1. f. 1; Boisd. Sp. Gén. Lép. p. 277. _P. Neesius_, Zink. Nov. Act. Acad. Nat. Cur. xv. t. 14. f. 1. _Hab._ Java (♂, ♀) (_Wall._), Penang (♂) (_Brit. Mus._). 18. PAPILIO NOCTIS, Hewitson. Tab. V. fig. 1 (♂)[12]. Footnote 12: