INDEX — GLOSSARY 



445 



Spider crab, Japanese, 307. 



Spiders, 316. 



Spider's threads, 316. 



Spinal cord, 321, 326, 330, 333. 



Spinal nerves, exit of, from backbone, 

 326. 



Spines, caudal, in Stegosaurus, 362 ; 

 haemal, in fish, 346; neural, in fish, 

 346 ; neural, in reptiles, 360, 367 ; 

 of echinoids, 166, 167, 168; of star- 

 fish, 150; upon shell, cause of, 220. 



Spinous shells, in evolution, 363. 



Spiny anteater, 378. 



Spiracle, 157, 158. 



Spiracles, presence of, in ancient 

 scorpions, 310. 



Spirals, brachidia as, 204, 204. 



Spirijer, 203-204 ; 5. cameratus, 204 ; 

 S. disjunct us, 204 ; S. increbescens, 

 188; S. mucronatus, 204, 204. 



Spirogyra, 35. 



Spirorbis, 146, 147; S. borealis, 147. 



Spleen, 330. 



Splenial bone, in reptiles, 367. 



SpUnts, of the horse's legs, 393, 3Q5. 



Sponges, 96-107; canals in, 96; classi- 

 fication of, 98 ; colonies of, 96 ; com- 

 mercial, 106; compared with Coelen- 

 terata, 102 ; compared with Protozoa, 

 100 ; digestion, etc., see Grantia ; 

 fossil, 103-105 ; geologic range of, 409 ; 

 glass, 104; individual, 96; not col- 

 onies of Protozoa, 97 ; paragastric 

 cavity of, 96 ; skeleton of, 97 ; spi- 

 cules of, 97. 



Spongilla, 96, 100, 106. 



Spongin, the horn^^ or fibrous substance 

 of many sponges, as of the common 

 bath sponge. It is an organic sub- 

 stance allied to silk, apparently of 

 variable composition, formed as a 

 cuticular secretion of certain cells 

 called sponginblasts. 



Sporangia, in the seed plants, 56. 



Spore-formation, in Protozoa, 88. 



Spores, 57 ; in ferns, 45 ; in plants, 30 ; 

 in Protozoa (Sporozoa), 95 ; in the 

 seed plants, 56 ; in the spermato- 

 phytes, 56. 



Sporophyte stage, 43 ; in the ferns, 45 ; 

 in the mosses, 42 ; in the seed plants, 

 56 ; in the spermatophytes, 56. 



Sporozoa, 95 ; geologic range of, 409. 



Spring-tails, 320. 



Spring wood, 71. 



Squalodonts, 399. 



Squamasal bone, in mammals, 325; in 

 reptiles, 367. 



Squamata, 367 ; evolution in, 367 ; geo- 

 logic range of, 367. 



Squids, 18, 255, 269, 26Q, 273 ; American, 

 273 ; in evolution, 83. 



Squilla, 308. 



Squirrels, 381, 382 ; habitat of, 374. 



Stag-moose, 383. 



Stamens, in angiosperms, 76. 



Starfish, 149-154, 150, 163. 



Statocyst, 283. 



Stegocephalia, 349, 352, 355; geologic 

 range of, 352; habitat of, 349, 352; 

 pineal opening present, 352 ; probable 

 derivation from crossopterygian fishes, 

 352; reason for inclusion with Am- 

 phibia, 352 ; sclerotic plates in, 335. 



Stegodon, 387, 388. 



Stegosaurus ungulatus, 361, 362, 363 ; 

 brain of, 363 ; in evolution, 363. 



Stentor, 95. 



Stephanosaurus marginatus, 19. 

 I Stephen formation, fossils from, 314; 

 geologic age of, 314. 



Sternbergia, 67. 



Sternum, of the cat, 323, 326. 



Stigma, 43, 76. 



Stigmaria, 53. 



Stigmata, 317. 



Stipule, 38. 



Stomach, see also under the various 

 classes ; in Amceba, 85 ; in the cat, 330. 



Stomach-stones, of dinosaurs, 358 ; of 

 plesiosaurs, 357. 



Stomatopoda, 308; geologic range of, • 

 308. 



Stone canal, 150. 



Stones River formation, fossil in, 244; 

 geologic age of, 244. - 



Stonewort, 35; food of the crayfish, 

 280. 



Straparollina remota, 240. 



Streptelasma, 132. 



Streptoneura, 243, 244. 



Stria;, fine lines upon the surface of shells. 



Stromatopora, 121. 



Strongylocentrotus, 166-171 ; S. dro- 



