5 6o 



INDEX 



Segmentation of egg, 60. 



Segments of worms, 189. 



Sella turcica, 498. 



Sense organ, 108. 



Sense organs of leech, 209; of mol- 

 luscs, 282. 



Sepia cultrata, 297, 301, 305. 



Septa, 121 ; of annelid worms, 191. 



Serpula, 198. 



Setae, of annelids, 190, 201 ; olfactory, 

 of Crustacea, 228 ; penial, 149, 150, 



153- 



Setigenous sac of annelids, 190. 



Shark, Greenland, 393. 



Sheath, proboscis, of nemertean 

 worms, 146. 



Sheep, 526, 537. 



Shell, Cephalopod, 300. 



Shell-fish, 266. 



Shell-gland of fluke-worm , 133. 



Shell-glands, 133 ; of Crustacea, 233. 



Shell membrane, 490 ; nacre of, 269 ; 

 periostracum, 269; prismatic layer 

 of, 269; supplemental, 23; vesti- 

 gial, 288. 



Shells, dextral, 285 ; sinistral, 285. 



Shields of reptiles, 439. 



Ship-worm, 279. 



Shoulder-girdle, of birds, 468; of 

 frog, 414. 



Shrew, 526 ; jumping, 542. 



Simiidae, 544. 



Sinistral shells, 285. 



Sinus venosus, 350, 407, 419. 



Siphon, of molluscs, 266 ; of gastro- 

 pod mollusc, 289. 



Siphonoglyphes, 115. 



Siphons of ascidians, 315. 



Siphonozooids, 118. 



Siphophora, 104. 



Siphuncle, 300. 



Siren, 433. 



Sirenia, 526, 536. 



Skeleton, 28, 67; of birds, 487; of 

 fish, 368; of sponges, 79. 



Skull, autostylic, 407; of birds, 467 ; 

 of frog, 410; of mammals, 495; 



of reptiles, 444; of vertebrates, 328, 



333. 337- 339- 



Slits, branchial, of sharks, 368 ; gill, of 

 Amphioxus, 326; of Balanoglos- 

 sus, 312. 



Sloth, 526, 531, 532. 



Slug, 288, 293. 



Snail, 284. 



Snake, 436, 446, 453 ; glass, 436 ; ovi- 

 parous, 455 ; viviparous, 455. 



Soldier ant, 253. 



Sole, 297. 



Solen, 281. 



Species, 3; abyssal, n; alpine, n; 

 littoral, ii ; pelagic, n, 24. 



Sperm, 59. 



Spermiduct of shark, 384. 



Sphaerophrya, 51. 



Sphenethmoid bone of frog, 411. 



Spicule, 31, 119. 



Spicule of sponge, 79, 88. 



Spider, 259. 



Spine, caudal, of Limulus, 262. 



Spines, ambulacral, 159; neural, 369. 



Spinnerets, 259. 



Spiracle of shark, 332, 368, 386. 



Spiroloculina, 25. 



Spirula peronii, 300, 301. 



Spleen, 375, 418; of birds, 476; of 

 mammals, 513. 



Sponges, 76. 



Spongelia, 87. 



Spongilla, 85, 89. 



Spores, 30. 



Sporocyst, 30, 134 ; of fluke-worm, 134. 



Sporoduct, 58. 



Sporozoa, 55. 



Spot, anal, 46. 



Spur of birds, 487. 



Squamata, 434. 



Squamosal bone, 414, 498. 



Squammulina, 22. 



Squid, 296, 300. 



Squirrel, 526, 541 ; flying, 541. 



Starfish, 157. 



Stentor, 49. 



Sternebrae, 336, 495. 



