Index 



375 



Reversion, 322 

 Rhizopods, 212 

 Rotifers, 7, 42, 234 

 Round-mpuths, 9, 252 

 Rudimentary organs, 277 



Saccophora, 62 



Sacculina, 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, 11, 222 

 Spongilla, 186 

 Spring, biology of, 95, 96 

 Starfish, 235 



Stickleback, courtship of, 99 



parental care of, 109, no, 122 

 Stinging-animals, n, 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, 19 

 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, 11, 228-235 



Yolk, 195 



Zoology, history of, 352-357 



THE END 



Printed by R. & R. Clark, Edinburgh 



