Index 



375 



Reversion, 322 

 Rhizopods, 212 

 Rotifers, 7, 42, 234 

 Round-mouths, 9, 252 

 Rudimentary organs, 277 



Saccophoea, 62 



SaccuUria, 48 



Sea-horse, parental care of, no 



Seasonal dimorphism, 314 



Segmentation, 195 



Sensations, 151 



Sex, 96 



Sexual reproduction, 186-188 



selection, 98 

 Shells of molluscs, 243 

 Shepherding, 119, 120 

 Shifts for a living, 46-66 

 Skunk, 55 



Snails and plants, 30 

 Snakes, 260-263 

 Social inheritance, 337-339 



life of animals, 67-94 



organism, 93, 94 

 Societies, evolution of, 87 

 Song of birds, 96 

 Spencer, 297, 298 

 Spermatozoon, 192, 193 

 Sphex, 121 

 Spiders, courtship of, 101-105 



bird-catching, 36 

 Sponges, II, 222 

 Spongilla, 186 

 Spring, biology of, 95, 96 

 Starfish, 235 



Stickleback, courtship of, 99 



parental care of, 109, no, 122 

 Stinging-animals, 11, 223-228 

 Storing, 120, 121 

 Struggle for existence, 32-45 

 Surrender of parts, 64-66 

 Symbiosis, 69 



Tapeworms, 229 

 Termites, 24, 84-87 

 Tissues, 179, 180 

 Tortoises, 263 

 Toxotes, 118 

 Trematoda, 229 

 Tunicates, 9, 250, 251 

 Turbellaria, 228 



Variation, 299 



Vertebrata, characters of, 19, 248, 



249 

 Vital force, ig 

 Vivarium, 20, 21 

 Volvox, 187 



Wallace, 296, 297 

 Warning colours, 55, 56 

 Weapons of animals, 34 

 Web of Life, 18-31 

 White Ants. See Termites 

 Worms, 10, II, 228-235 



Yolk, 195 



Zoology, history of, 352-357 



Printed by R. & R. Clakk, Edinburgh. 



