INDEX 
Abomasum, 68. 
Actinocephalus al (ill.), 
14. 
Adaptations, . 113, 128; ; classifica- 
tion 6f,-128 ; 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 mace (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. 
.Amoba, 5; multiplication of (ill.) 53. 
Amoeba 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. . adn. ost 
Anosta ovina: metamorphosis 
of (illus.), 92; mimicked iby: Ba- 
. stlarchia archippus:(illus.), 2191 
| Antenna of eray-fish (illus.), 283.; 
of leaf-eating beetle (illus.), 230. 
Antenne, 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.), 
288; of cricket (illus.), 234; of 
grasshopper (illus.), 234; .of mol- 
lusk (illus.), 233; of mosquito 
(illus.), 235. 
Auditory organs, 282. 
Australian realm, 303. 
Aythya (illus.), 137. 
Barbadoes earth, 19. 
Barnacle, adult and larva (illus.), 
195; metamorphosis of (illus.), 
101. 319 
