General prevalence of protective colouring among caterpillars, 289. Polymorphic adaptive colouring in _C. Elpenor_, _C. Porcellus_, _P. Œnotheræ_, _D. Vespertilio_, _D. Galii_, _D. Livornica_, _D. Hippophaës_, 295. Habit of concealment primary; its causes, 298. Polymorphism does not here depend upon contemporaneous but upon successive double adaptation; displacement of the old by a new adaptation; proof in the cases of _D. Hippophaës_, _D. Galii_, _D. Vespertilio_, _M. Stellatarum_, _C. Elpenor_, and _S. Convolvuli_, 300. V. _Biological Value of special Markings_, p. 308. Four chief forms of marking among _Sphingidæ_, 309. Complete absence of marking among small caterpillars and among those living in obscurity, 310. Longitudinal stripes among grass caterpillars, 312. Oblique striping. Coloured edges are the shadows of leaf ribs, 317. Eye-spots and ring-spots. Definition, 326: Eye-spots not originally signs of distastefulness, 328; they are means of alarm, 329; experiments with birds, 330; possibility of a later change of function in eye-spots, 334. Ring-spots. Are they signs of distastefulness? Are there caterpillars which are edible and which possess bright colours? 335; experiments with lizards, 336. In _D. Galii_, _D. Euphorbiæ_, _D. Dahlii_ and _D. Mauritanica_ the ring-spots are probably signs of distastefulness, 341. In _D. Nicæa_ they are perhaps also means of exciting terror, 342. The primary ring-spot in _D. Hippophaës_ is a means of protection, 344. Subordinate markings. Reticulation, 347. The dorsal spots of _C. Elpenor_ and _C. Porcellus_, 348. The lateral dots of _S. Convolvuli_, 348. Origination of subordinate markings by the blending of inherited but useless markings with new ones, 349. VI. _Objections to a Phyletic Vital Force_, p. 352. Independent origination of ring-spots in species of the genus _Deilephila_, 352. Possible genealogy of this genus, 358. Independent origination of red spots in several species of _Smerinthus_, 360. Functional change in the elements of marking, 365. Colour change in the course of the ontogeny, 367. VII. _Phyletic Development of the Markings of the Sphingidæ. Summary and Conclusion_, p. 370. The oldest _Sphingidæ_ were devoid of marking, 370. Longitudinal stripes the oldest form of marking, 371. Oblique striping, 373. Spot markings, 375. The first and second elements of marking are mutually exclusive, but not the first and third, or the second and third, 377. Results with reference to the origin of markings; picture of their origin and gradual complication, 380. General results; rejection of a phyletic vital force, 389. =II.= ON PHYLETIC PARALLELISM IN METAMORPHIC SPECIES. _Introduction_, p. 390. I. _Larva and Imago vary in Structure independently of each other_, p. 401.