INDEX 



421 



Seasonal variation, 177 

 Sea urchin, 330, 340 

 Seaweeds, 238 

 Sebastodes, 331 

 Sedentary, 61, 322 



constituents, 335 



organisms, 34 

 Seed, crop, 126, 180 



-eating birds, 127 

 Seeds and fruits, 118 

 Serai-pools with gravel bottoms, 308 

 Senecio aureus, 272 

 Sense of direction, 227 

 Serai, 12 



communities, 27, 247 



stages, 231, 232, 260-286, 312 

 coastal prairie, 280 

 mixed prairie, 266, 267 

 true prairie, 276 

 Sere, 6, 27, 56, 229-250 

 Serpulid, 54, 100 



worms, 54 

 Serrivomer, 318 

 Serule, 238 

 Sessile, 61, 322 



animals, 53 



organisms, 34 



plants, 53 

 Setaria macrostachya, 282 

 Settlement, 108 



effect, 108 

 Shad, 300, 305 

 Shadbush, 232 

 Sharks, 201 



Sharp-tailed grouse, 174, 197 

 Sheep, 120 

 Sheepshead, 300, 306 

 Shelled animals, 101 

 Shells, 75, 100 

 Shelter, 11, 109, 112, 119 

 Shifting sand-bottomed pools, 308 

 Shore crab, 326 

 Short-eared owl, 190 

 Short-grass disclimax, 261 

 Short-grass plains, 120 

 Short-headed red horse, 300 

 Shrew, 132 



Shrimp, 319, 320, 331, 332 

 Siberian nutcracker, 196 

 Sidalcea, 288 



Silphium, 272, 279 



Sinter, 75 



Siraplankton, 14 



Sistrurus, catenatus, 231, 274 



Sisymbrium altissimum, 293 



Sisyrinchium bcllum, 287 



Skeletons, 73 



Skink, 267 



Skuas, 190 



Skunk, 132, 193, 265 



common, 133 



hog-nosed, 132 



spotted, 280 

 Slumping, 7, 78 

 Small-mouthed buffalo, 305 

 Small-river climax, 300 

 Smith's longspur, 253, 265 

 Snail, 54, 98, 275, 300, 306, 308, 328, 



330, 331, 333, 336, 339 

 Snakes, 133, 265, 274 



blue racer, 274 



bull, 257, 290 



crotalid, 107, 231, 274, 276, 285, 

 290 



garter, 256, 274 



gopher, 290 



hog-nosed, 267 

 Snapping turtle, 301 

 Snowshoe rabbit, 112, 192, 194 

 Snowy owl, 190 

 Social community, 6 

 Social grouping, 109 

 Social hunting, 132 

 Social life, 206 



Social organization, 131, 132 

 Socies, 240 

 Society, 245, 148 



human, 24 



layers, 245-246 



seasonal, 240 

 Soil, 78, 84 



profile, 90, 91 



structure, 78 



water, 87 

 Solanum, rostratum, 117 



tuberosum, 117 

 Solen, 181. 348 



pellucidus, 182 

 Solidago, 288, 292 



nemoralis, 273 



