424 



PRINCIPLES OF ANIMAL BIOLOGY 



Tapeworm, 265, 266 



Tarsals, 93 



•Taxonomic groups, 259-280 



Taxonomic ranks, adaptation in, 363, 364 



Taxonomy, 20, 21 



evolutionary basis of, 250, 251 



history of, 244-247 



practical, 257, 258 



principles of, S44-258 



relation of, to other biology, 258 

 Telolecithal egg, 199 



cleavage of, 201 

 ^Pelophase, 56, 58, 59 

 'J'empeiature, affecting reactions, 282 



causing mutation, 283 



effect of, on animals, 281-2o3 



modifying structure, 283 

 Tentacles, 172, 173, 174, 175 



of Hydra, 71, 72 

 Teredo, 271 

 Termites, dependence of, on proto;:oa, 



287, 288 

 Tertiary, 330 

 Testis, 153, 156, 178 



of earthworm, 168 



of Hydra, 72 

 Testosterone, 156 

 Tetrads, 194, 195, 197 

 Thales, 2 



Thamnophis, distribution of, 315, 316 

 Theophrastus, 5 

 Thermocline, 296, 297, 298 

 Thiamin, 111 



Thoracolumbar nervous system, 147 

 Thricozoa, 247 

 Thrombase, 130 

 Throml)oplastin, 130 

 Tliynnis, 153, 156 

 lliyroid, 153, 154, 155, 156 

 Thyroxin, 154 

 Tibia, 93 

 Tissues, 81-85 

 a-tocopherol, 112 

 Tongue, of frog, 102 

 Trachea, 115, 116 



in embryo, 21 1 

 Tracheal gills, IKi 

 Tracks, fossil, 327, 328 

 Transplantation, embryonic. 218 



Transverse process of ^■ertebl•;^, 91 



Tree frf)g, carrying eggs. 188 



Trematoda. 265, 266 



Triassic, 330, 335 



Triceratops, 332, 335 



Trichinella, 266, 267 



Trilobites. 331, 332 



Trilophodon, 336, 337, 339 



Trochophore, 269 



Trypsin, 105 



Trypsinogen. 105 



Tubular gland, 84 



Tunicata, 276, 278 



Turbellaria, 265, 266 



Turtle, 277 



Tympanum, in embr^vo, 211 



Type, taxonomic, 249, 250 



Typhlosole, earthworm, 102 



I' 



Ulna, 93 



Umbilical vessels, 184 



Unconformity, 329 



Uniformitarianism, 360 



Unit characters, 223 



Universal symmetry. 78 



Urea, 133, 134 



Ureter, 136, 137, 178, 179 



Urethra, 137, 179 



Urine, 137 



Uriniferous tubule, 135, 136 



TTrinogenital system, 177-179 



Uterus, 178, 179, 180, 184, 185 



V 



Vacuole, 26, 27 

 Vagina, 179, 180 

 Valence, 3*1 



Vasa deferent ia, 179, 180 

 Vasa (>fferentia, 178 

 of earthworm, 168 

 Vascular tissue, 81. 85 

 Vaucheria, as a syiic\'tiuin, 66 

 Vegetation areas, 312 

 Vegetative pole, 199 

 Veins, 122. 123, 129 

 Ventricle, 123, 124 

 Vermiform appendix, 103 

 Vertebra, 80, 91 



