INDEX 
Sarcoptes scabet (illus.), 188. 
Scelophorus undulatus (illus.), 185. 
Scorpion (illus.), 134. 
Scyphozoa, 37; development of, 38, 
Sea-anemone, 40. 
Sea-cucumber (illus.), 143; regen- 
eration of, 145. 
Sea-lily (illus.), 148. 
Sea-mat (illus.), 68. 
Sea-urchin (illus.), 141. 
Sea-squirt (illus.), 152, 
Sedentary life, effect of, 62. 
Segments, of worms, 55; of arthro- 
pods, 94, 
Segmented worms, 565. 
Serpentes, 186. - 
Serpent-star (illus.), 141. 
Serphus dilatatus (illus.), 122. 
Serputla (illus.), 62. 
Serpulids, 62. 
Seta, 55. 
Sexual reproduction, 32. 
Shark (illus.), 159. 
Shell-gland, 108. 
Shipworm, 75. 
Shrew, 234. 
Shrimp, fairy, 94; opossum (illus.), 
100. 
Silk-moth (illus.), 127. 
Silver-spot butterfly (illus.), 126. 
Simple animals, characteristics of, 
18. 
Single-celled animals, 11. 
Sinus, blood, 78. 
Siren (illus.), 178. 
Slug (illus.), 80. 
Snail, common (illus.), 80; arma- 
dillo (illus.), 82 ; naked (illus.), 82. 
Snakes, 186; distribution of, 193. 
Snipes, 216. 
Somateria dresseri (illus.), 214. 
Species, origin of, 91. 
257 
Sperm-cell, 20. 
Sphenodon punctatus (illus.), 199. 
Spicule, of sponge (illus.), 26; of 
coral, 42. 
Spiders, organization of, 185; hab- 
its, 136. : 
Spinnerets, 185. 
Spiny-rayed fishes, 166.. 
Sponge, development of (illus.), 
21; distribution, 22; shape and 
structure, 23. 
Spontaneous generation, 54. 
Springtail, 117. 
Squalus acanthias (illus.), 159, 
Squash-bug, 122. 
Squid (illus.), 87. 
Squirrels, 238. 
Starfish (illus.), 140; regeneration, 
145; structure, 146. 
Steganopodes, 212. 
Stickleback, 164. 
Structure and function, correla- 
tion of, 6. 
Strongylocentrotus purpuratus (il- 
lustration), 144. 
Struthio camelus (illus.), 210. 
Sturgeon (illus.), 161. 
Sunfish (illus.), 166. 
Symmetry, radial and bilateral, 44. 
Swan (illus.), 218. 
Swift, 222. 
Tenia solium (illus.), 51. 
Tapeworm (illus.), 50; develop- 
ment, 51; in relation to regen- 
eration, 51. 
Tarantula (illus.), 137. 
Teeth, use of, 2. 
Teleostei, 160. 
Termites (illus.), 120. 
Tern, 211. 
Terrapene carolina (illus.), 189. 
