Stainton, H. T., larval characters of _Notodontidæ_, 443; young larvæ of _Triph. pronuba_, 520. Staudinger, Dr., seasonal dimorphism of _Euch. Belia_ and _E. Ausonia_, 3, 48; butterflies of Finnmark, 20; _P. Napi_ var. _Bryoniæ_ from Lapland, 44, 49; larvæ of _Ch. alecto_, 193; affinities of _Nymphalis_ and _Apatura_, 438. _Stauropus Fagi_, protective habits of larva, 290. Sterility, causes of, 596; a result of reversion, 597; law of, in reversion forms, 599. Stoat, seasonal change of colour, 7. Strauch, “Revision of _Salamandridæ_” referred to, 570, 577. Strecker, H., N. American species of _Smerinthus_, 453. Stripes, longitudinal, 312, 372; oblique, 317, 373. T. Tadpoles, arrested development, 607. Tegetmeier, W. B., metamorphosis of _Siredon_, 566. Teleology and Mechanism, 694. _Terebrantia_, larvæ, 508. Transformation, causes of, 460, 496; factors of, 676. _Trematoda_, alternation of generations in, 83. Trimen, Roland; larva of _Lopho. Dumolinii_, 527; of _Ch. Capensis_, 529; phytophagic variability of larva of _Ach. Atropos_, 531. _Triptogon roseipennis_, larva, 244. _Triton_; _T. alpestris_, sexual larva, 585; reproductive larvæ, 590. Degeneration in genus, 612. Species of Upper Engadine, 631. Typical parts, modified by environment, 501, 513. U. Upper Engadine; Amphibia, 615; climate, 616; frog from, 618; Tritons of, 631. Urea, synthesis of, 643. V. _Vanessa._ _V. Urticæ_, climatic variation, 60; _V. Atalanta_, _Urticæ_, and _polychloros_, variable in two stages, 405; _V. Io_, variable in one stage, 407. Congruence and incongruence in genus, 446; phyletic completeness of, 447; arrangement of spines on larvæ, 448. Variability, origin, 107; limited, 114, 362, 653, 655; independent in different stages, 402; definition of, 404; a relative term, 408; causes of, in pupæ, 411; primary and secondary, 416; independent in different larval stages, 416; phytophagic, 305, 531; Von Hartmann’s views, 646; not unlimited, 647, 652, 655, 683; factors of, 676, 684; mechanical theory of, 677; individual, 681, 685. Variation; climatic, 45, 686; causes of, 105; analogous, 683; abrupt not inherited, 701. Varieties, climatic, distinct from local, 45. Velasco, Señor, Axolotl of L. St. Isabel, 626. Vital force, phyletic, elimination of, 287; objections to, 352, 461, 511, 518; ontogenetic, abandonment of, 641, 687. W.