INDEX. 



479 



Rachis (see feather) 



Radial symmetry, 85, 86 



Radiolaria, 153, 154 



Radula, 243 



Rail, 412 



Rana, 378 



Raptores, 417 



Rat, 444 



Ratitse, 408 



Rattle-snake, 383 



Rays, 368 



Razor-clam, 253 



Receptaculum seminis, 227 



Rectrices (see feathers) 



Redia, 189, 190 



Reduction divisions, 30, 31 



Reference books, 466 



Regeneration, 89 



Remiges (see feathers) 



Renal portal circulation, 362 



Reproduction, 13; of cells, 22; asex- 

 ual, 68 ; sexual, 68 



Reproduction, organs of protozoa, 

 149 ; porifera, 161 ; coelenterata, 175 ; 

 unsegmented worms, 184, 189, 191; 

 echinoderms, 211; annulata, 226; 

 mollusks, 248, 249 ; arthropods, 282 ; 

 vertebrates, 341 ; fishes, 366 ; am- 

 phibia, 376 ; reptiles, 387 ; birds, 

 403 ; mammals, 437 



Reproductive epithelium, 46 



Reptilian birds, 407 



Reptiles, 136, 380; age of, 381 



Resemblance, general and special, 119 



Respiration, 62 ; internal, 334 ; in pro- 

 tozoa, 147; coelenterata, 174; an- 

 nulata, 225 ; echinoderms, 208 ; 

 mollusks, 244 ; arthropods, 278 ; 

 vertebrates. ^4 ; fishes, JUA. ; am- 

 phibians,^24 ; reptiles, 384 ; birds, 

 401 ; mammals i 436 



Respiratory tree, 209 



Retina, 77, 78, 352, 353 



Rhinoceros, 442 



Rhamphorhynchiis , 386 



Rhinoderma, 376 



Rhizopoda, 153 



Rhodostethia, 210 



Right-left axis (see symmetry) 



Rodentia, 444 



Rotifers, 194, 195 



Round worms, 193 

 Rumen, 434 



Ruminant, 442 



Ruminant stomach, 332, 434 



Sacral vertebrae, 327 

 Sagittal section, 83 



Salamander, 379 



Salmo, 364 (salmon) 



Salvelimus, 365 



Sarcolemma, 53 



Saururae, 407 



Scales, 359 



Scallop, 254 



Scarabeids, 302 



Sceloporus, 389 



Schwann's sheath, 55 



Sciurus, 445 



Scolopendra, 293 



Scorpionida, 303 



Scyphistoma, 177 



Scyphozoa, 177 



Sea-cow, 441 



Sea cucumber, 214 



Sea lilies, 213 



Sea squirts, 308 



Sea urchins, 203 



Seals, 443 



Secretion, 16, 61 



Sections, defined, 83 



Segment, 275 (see metamere, somite) 



Segmentation (see cleavage, meta- 

 merism) 



Segmentation cavity, 33, 34 



Segmented worms (see annulata) 



Semi-circular canals, 351 



Seminal vesicles, 227 



Sensation, 70, 148 ; see also sense or- 

 gans 



Sense organs protozoa, 148 ; porifera, 

 161 ; coelenterata,i75 ; echinoder- 

 mata, 211 ; annulata, 226; mollusca, 

 247; arthropoda, 281; vertebrata, 

 349 ; reptiles, 385 ; birds, 401 ; mam- 

 mals, 436 



Sensory epithelium, 44, 45 



Serous membrane, 42 



Sexual cells, 28 (see ovum, sperm) 



Shark, 368 



Sheep, 442 



Sheepshead (fish), 370 



Shell, 240, 241 ; structure, 242 



Shipworm, 253 



Shrike, 425 



Shrimp, 289 



Shrews, 446 



Sight, 76 (see sense organs) 



Silk worm, 300 



Siphon, 236, 251, 252 



Siphonophora, 177, 180 



Sipunculoidea, 233 



Siren, 377, 379 



Sirenia, 441 



Skates, 368 



Skin, 322 (see integument) 



