_Pristis pectinatis_, 281. Protophyta, 82. Protoplasm, described, 39. _Protopterus_, 288. Protozoa, defined, 43, 75; form of, 78; marine, 80. _Pseudemys_, 313. _Pseudogryphus californianus_, 352. Psittaci, 353. Ptarmigan, 356. Puff-adder, 325. Puffins, 345. _Pulex irritans_, *204. Pulmonata, 253. Puma, 398. Pumpkin seed, life of, 270; structure of, 263. Pupa, 189; cross-section of body of, honey-bee, *191. Pupation, 189. _Purpura saxicola_, *248. Pygopodes, 343. Python, 324. Quail, 350. _Querquedula discors_, 347. Rabbits, 390. Radiolaria, 80. Rail, Carolina, 349. _Raja erinacea_, 280, *281. _Raja lævis_, 281. _Rana catesbiana_, 299. _Rana palustris_, 300. _Rana sylvatica_, 300. _Rangifer caribou_, 396. Raptores, 351. Ratitæ, 341. Rats, 391. Rattlesnake poison-fangs, *324. Rattlesnakes, 321. Rattles of rattlesnake, *223. Reefs, coral, 106. Reindeer, 396. Remora, *287. _Remoropsis brachyptera_, *287. Root-cage, 460. Reptiles, body form and organization of, 309; classification of, 312; life-history of, 312; structure of, 310. Reptilia, 303. Resemblance, protective, 326. Rheas, 343. Road-runner, 354. Robber-ant, 225. Robin, Western, *368. Rock-bass, 282. Rock-crab, *153. Rock-dove, 351. Rodents, 390. _Rosalina varians_, *81. _Rotifer_ sp., *143. Round worms, 140. Ruminants, 395. _Sacculina_, 67, *418. Sage-hen, 350. Salamander, red-backed, 297; tiger, *292. Salamanders, 297. _Salmo irideus_, *283. Salmon, king, 284. Sand-dollar, 124. Sand-pipers, 345. _Sanninoidea existiosa_, *212. Sap-sucker, downy, 355; hairy, 355. Saw-fish, 281. _Sayornis nigricans_, nest and eggs of, *340. Scale insect, red-orange, *198. Scale insects, 198. Scale rose, *198. Scales of wings of Lycæna, *206; wing of Monarch butterfly, *174. Scallops, 246. _Scalops aquaticus_, 391. _Scaphiopus_, 300. _Sceloporus_, 317. _Sciuropterus volans_, 391. _Sciurus carolinensis_, 391. _Sciurus hudsonicus_, 391. _Sciurus ludovicianus_, 391. _Scolopendra_ sp., 228, 229. Scorpion, *230. Scorpions, 229. _Scotiaptex cinera_, 353. Screech-owl, *352, 353. _Scutigera forceps_, *228. Scyphozoa, 97, 101. Sea anemones, 92, 102, *103. Sea cucumber, *125. Sea-cucumbers, 108, 121, 124. Sea-fan, 107. Sea-feather, 106. Sea-horse, *285. Sea-lamprey, 279. Sea-lily, 118. Sea-pen, 106. Sea-shells, 252. Sea-slugs, 255. Sea-snakes, 325. Sea-squirt, *261. Sea-turtles, 315. Sea-urchin, *114; structure of, 113. Sea-urchins, 108, 121, 123. Seals, 397. Selection, artificial, 409; natural, 406. Sembling of insects, 176. Sepias, 256. Setting-board for butterflies, *466, 467.