INDEX. 



[The names of the genera cited are printed in italics. The numerals refer 

 to pages. Those in bold-faced type indicate that the object is illustrated on 

 that page.] 



Absorption, 61 



Abyssal fauna, 129 



Acalephs, 242 



Acanthopteri, 369 



Acclimatization, 12, 98 



Achromatin, 20, 26 



Acquired characters, 100 



Actinozoa, 177 



Adaptation, means of, 98 ; types of, 

 104 ; to inorganic environment, 105 ; 

 to mates, 107; to offspring, 108; 

 social, 112, 113; competitive, 114; 

 commensal, 116; symbiotic, 116; to 

 preying, 118; for protection, 119 



Adaptive habits and instincts, 126 



Adipose tissue, 48 



Aepyornis, 409 



Aerial fauna, 130. 



Air-sacs (birds), 401 



Aix, 408 



Albatross, 411 



Alimentary canal (see Digestive sys- 

 tem). 



Allantois, 387, 405 



Alligator, 392 



Allolobophora, 216 



Alternation of generation in Coelen- 

 terates, 172; in worms, 189, 190 



Alveoli, 436 



Ambulacral system, 207, 210 



Amitotic cell division, 23 



Ammonites, 259 



Amnion, 387, 405 



Amoeba, 13, 22, 84, 142, 145 



Amphibians, 137, 372 



Amphioxus, 309, 310 



Amphitrite, 231 



Amphiuma, 377 



Ampullae, 207, 210 



Anabolism, 60 



Anacanthini, 369 



Analogy, 78 



Anaphase, 23 



Anatomy, 3 



Animalcules (see Protozoa) 



Annelids (see Annulata) 



Annulata, 139, 216, 230 



Anoaonta, 234, 253 



Ant-eater, 439, 441 



Antenna, 263 



Antennule, 263 



Antero-posterior (see symmetry) 



Antimeres, 87 



Ants, 114, 303 



Anura, 379 



Aorta, 337 (see circulatory system) 



Apes, 447 



Aphis (plant lice), 296 



Appendages arrangement of, 88 ; in 



arthropods, 275 ; in vertebrates, 322 ; 



in fishes, 356 ; in amphibians, 373 ; 



in birds, 397 ; in mammals, 429 

 Appendicular skeleton, 328, 329 

 Appendix, 455 

 Aptera, 293 

 Apteryx, 406 

 Aquatic fauna, 129 

 Arachnida, 303 

 Araneida, 304 

 Arbacia, 214 

 Archccopteryx, 406 

 Archenteron, 33, 35 

 Archipterygium, 357 

 Ardea, 410 

 Argonauta, 258 

 Aristotle's lantern, 203, 207 

 Armadillo, 441 

 Army-worm, 300 

 Arterial arches, 337, 338 

 Arteries, 64 (see circulatory system) 

 Arthropoda, 138, 261 

 Artificial selection, 97 

 Artiodactyla, 442 

 Ascaris, 193 

 Ascidians, 309 

 Asellus, 265 

 Ass, 443 



Assimilation, 12 (see metabolism) 

 Asterias, 200 

 Asteroidea, 213 

 Astroid-stage, 23 (cell-division) 



471 



