Sacc, on sterility of _Amblystoma_, 593.
Salamanders, habits of Italian land species, 617;
oviposition of, 630.
_Salamandra atra_, experiments with, 615.
_Salamandrina_, characters of, 577;
_S. perspicillata_, habits of, 617.
Sars, development of _Leptodora hyalina_, 94.
_Saturnia._
_S. Yamamai_, variable in first stage only, 406;
_S. carpini_, development of larva of local forms, 419.
_Satyrinæ_, hibernation of larvæ, 73.
Saussure, De, on _Siredon Mexicanus_, 565, 602;
physical character of Mexican Lake, 603.
Saw-flies, protective habits of larvæ, 290.
Schmankewitsch, transformation of _Artemia_, 635.
Schmidt, Oscar, on convergence of character, 396, 459;
on variability, 654.
Schreibers, sexual _Triton_ larvæ, 591;
arrested tadpoles, 607.
Schulze, F. E., parasitism in _Medusæ_, 699.
Science, function of, 640.
Scudder, S. H., embryonic larvæ of butterflies, 166.
Seasonal dimorphism, origin and significance, 1;
seasonal change of colour in animals, 7;
and climatic variation, 45;
seasonal adaptation in caterpillars, 305.
Seidlitz, reproduction of Axolotl, 571;
white var. of hare, 662.
_Selenia tetralunaria_, _S. illunaria_, _S. lunaria_, and
_S. illustraria_, seasonal dimorphism, 4.
Semper, C., origin of alternation of generations, 84;
transformation of _Amblystoma mavortium_, 629.
Semper, G., young Sphinx-larvæ, 166;
figures of caterpillars referred to, 522.
Senses, physiology of, 711.
Sepp, figure of caterpillar referred to, 262.
_Sesiidæ_, affinities of, 370.
Sexual dimorphism, of butterflies, 32, 250;
of caterpillars, 308, 527, 534;
secondary sexual characters, 62;
sexual selection, 69, 102.
Siebold, Von, on _Pulmonifera_, 590.
_Siredon._ _S. Mexicanus_, habits, 565;
_S. lichenoides_, transformation, 567, 630;
phyletic advance of genus, 584;
retention of genus, 610;
_S. tigrinus_ from L. St. Isabel, 626.
Slater, J. W., food of gaily coloured caterpillars, 294.
_Smerinthus_, larvæ of, 232;
_S. Tiliæ_, 233;
4th stage, 235;
_S. Populi_, 236;
and stage, 237;
3rd and 4th stages, 238;
5th stage, 239;
_S. ocellatus_, 240;
dimorphism of larva, 241;
_S. Tiliæ_, variable in two stages, 405;
North American species of, 453;
_S. tatarinovii_, and _S. planus_, larvæ, 244.
Species, causes of transformation of, 116;
nature of, 671.
Specific characters, 91;
may originate through direct action, 100.
Specific constitution, 112.
Spencer, Herbert, theory of descent, 645;
variability, 654;
law of growth, 655.
Spermatozoa, of _Amblystoma_, 593;
of _Lissotriton punctatus_, 595.
Speyer, Dr., seasonal dimorphism of moths, 4;
of _P. phlæas_ in Germany, 50.
_Sphingidæ_, oviposition, 164;
congruence and incongruence in genera, 450.
_Sphinx_-markings, ontogeny and morphology, 177.
Larvæ of genus, 259;
_S. Convolvuli_, 650.
Origination of markings, 273;
law of development, 274;
forms of markings, 309;
_S. Ligustri_, constant in three stages, 405.
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.