INDEX 



Abomasum, 68. 



Actinocephalus oligacanthus (ill.), 

 14. 



Adaptations, 113, 123; classifica- 

 tion of, 123 ; concerned with sur- 

 roundings, 143 ; degree of struc- 

 tural change in, 146 ; for defense 

 of young, 137 ; for rivalry, 135 ; 

 for self-defense, 128 ; for secur- 

 ing food, 125 ; origin of, 123. 



Agassiz's cave-fish (illus.), 282. 



Albula vulpes, metamorphosis of 

 (illus.), 98. 



Alimentary canal, 66 ; of cock- 

 roach (illus.), 73 ; of earthworm 

 (illus.), 71 '; of flatworm (illus.), 

 70; of Holothurian (illus.), 70; 

 of mussel (illus.), 72 ; of Obelia 

 (illus.), 69 ; of ox (illus.), 67 ; of 

 Planaria (illus.), 70 ; of sea- 

 cucumber (illus.), 70. 



Alligator (illus.), 290. 



Alluring coloration, 216. 



Alternation of generations, 42. 



Altricial, 140. 



Amoeba, 5; multiplication of (ill.) 53. 



Amc&ba polypodia (illus.), 8. 



Anatomy, 64. 



Andrena, nest of (illus.), 160. 



Andricus californicus, galls of 

 (illus.), 143. 



Angler, deep-sea (illus.), 124. 



Animals, life of simplest, 1 ; many- 

 celled, 2 ; one-celled, 2 ; slightly 

 complex, 24. 



Anosia plexippus, metamorphosis 

 of (illus.), 92 ; mimicked by Ba- 

 silarchia archippus (illus.), 219. 



Antenna of cray-fish (illus.), 233 ; 

 of leaf -eating beetle (illus.), 230. 



Antennae, specialized, of prome- 

 thea moth (illus.), 231. 



Antrostomus vociferus (illus.), 203. 



Ants (illus.), 155. 



Anus, 68. 



Appearance, terrifying, 212. 



Arctic realm, 297. 



Area, faunal, 296. 



Artificial selection, 120. 



Auditory organ of cray-fish (illus.), 

 233; of cricket (illus.), 234; of 

 grasshopper (illus.), 234 ; of mol- 

 lusk (illus.), 233; of mosquito 

 (illus.), 235. 



Auditory organs, 232. 



Australian realm, 303. 



Aythya (illus.), 137. 



Barbadoes earth, 19. 



Barnacle, adult and larva (illus.), 

 195; metamorphosis of (illus.), 

 101. 319 



