IJSDEX. 



691 



Silverfish, 477 

 Simia, 651 

 Simiidse, 651 

 Simuliidge, 493 

 Sinupalliata, 368 

 Sinus frontalis. 539 

 Sinus, sphenoid, 539 

 Siphon, 345, 387, 360 

 Siphonaptera, 493 

 Siphonophora, 240, 243 

 Siphonophores, 166 

 Siphonostomate, 371 

 Siphonostomata, 422 

 Siphuncle, 388 

 Sipunculoida, 317 

 Sipunculus, 317 

 Siredon, 36 

 Siren, 586 

 Sirenia, 644 

 Sirex, 485 

 Siricidse, 486 

 Sixth sense, 125, 538 

 Skalis, 571 

 Skin, 76 

 Skull, 519 



Skull of mammals, 619 

 Skunk, 647 

 Skylark, 616 

 Slime animals, 198 

 Slime eels, 557 

 Slime moulds, 198 

 Sloths, 636 

 Smell, organs of, 126 

 Smelt, 576 

 Snakes, 600 

 Snapping turtle, 596 

 Snout beetles, 485 

 Snow flea, 477 

 Social animals, 167 

 Soft- shell crab, 437 

 Soft-shelled turtle, 596 

 Solasteridse, 337 

 Sole, 578 

 Solemyidse, 367 

 Solen, 368 

 Solenoconchse, 369 

 Solenogastres, 358 

 Solenoglypha, 60 1 



Solenoglyphic tooth, 600 



Solenidse, 368 



Solidungula, 641 



Solifugae, 449 



Solpuga, 450 



Solpugida, 449 



Somatic cells, 143 



Somatic layer, 159 



Somatopleure, 159 



Somites, 305 



Song birds, 616 



Sorex, 637 



Soricidse, 637 



Sowbug, 442 



Spadella, 298 



Spadix, 238 



Spanish flies, 484 



Span worms, 494 



Spatangoidea, 346 



Species, 10 



Species, nature of, 19, 25 



Species, physiological characters of, 27 



Spelerpes, 587 



Speotyto, 617 



Spermaceti, 646 



Spermatophore, 392 



Spermatozoa, 81 



Spermatozoids, 202 



Sperm nucleus, 149 



Sperm whale, 646 



Sphaeridia, 330 



Sphasrogastrida, 451 



Sphseroma, 442 



Sphaeromidae, 442 



Sphaerophrya, 212 



Sphaerozoidae, 195 



Sphargis, 595 



Sphenethmoid bone, 581 



Sphenodon, 596 



Sphenoidalia, 521 



Sphenoid bone, 523, 620 



Sphenoid sinus, 539, 624 



Sphenopalatine ganglion, 537 



Sphenotic bone, 522 



Spherical animals, 135 



Sphingina, 495 



Sphyranura, 274 



Spicula, 300 



