Tænioïdæ, characters of, ii. 144 Talitrus, or sand-hopper, structure of, ii. 201, 202 Tar, coal. _See_ Coal tar Tardigrada, characters of the, ii. 161 Tartaric acid, chemical combination forming, i. 97 Tea, active principle of, i. 428 Tellurium, atomic weight of, i. 105 its properties analogous to those of sulphur and selenium, i. 105 Terebella conchilega, structure of, ii. 153-155 Textularia, structure and habitat of the genus, ii. 41 fossils of, ii. 42 Textularia Mayeriana, form of, ii. 28 Thalassicolla morum, structure of, ii. 21 Thalassicollæ, structure of, ii. 21 Thalassiophyllum Clathrus, habitat and structure of, i. 250 Thallium, i. 3, 4 effect of the spectrum from an electric spark between points of, i. 64 atomic weight of, compared with that of hydrogen, i. 100 Mr. W. Crookes’s discovery of the metal so called, i. 136 spectrum analysis of, i. 137 properties of, i. 137 where found, i. 137 changes in the spectrum of, by high temperature, i. 144 Thallus or frond, of lichens, i. 301 Thaumantia pilosella, form and structure of, ii. 92 otolites of, ii. 93 mode of reproduction of, ii. 94 Thorinum, i. 4 Thunder-dirt of the New Zealanders, i. 268 Thyme, absorption of radiant heat by the perfume of, i. 44 Timmia, leaves of, i. 330 Tobacco, spectrum analysis of, i. 136 Tobacco, narcotic effect of, and as a relief from hunger, i. 428 Toluidine, property of, in producing the aniline colours, i. 122 Toluol, constituents of, i. 121 Topaz, oriental, i. 4 Torula cerevisiæ, structure, development, and cell-multiplication of, i. 287 Transparency in liquids and solids synonymous with discord, i. 36 causes of transparency, i. 37 Transpiration of gases, i. 110, 114 Tree ferns, structure of, i. 341 Trees, constitution of the stems of, i. 174 Tremellini, structure, habitat, and fructification of, i. 266 Trepang, used as food, ii. 184 Triceratium favus, structure and habitat of, i. 199 Triceratium genus, structure and habitat of, i. 199 Trichodesmium erythræum, structure, habitat, and reproduction of, i. 215, 216 Trichogastres, characters of the group, i. 267 Trichomanes radicans, or bristle fern, structure and habitat of, i. 361 Trichomanineæ, characters of the group, i. 345 characters and habitat of, i. 360, 361 Trilobites, structure of, ii. 203 Tripe de Roche, structure of, i. 308 Triphragmium dubens, spores of, i. 276 Tripoli stone on the Rhine, of what it consists, i. 206 Trochus granulatus, structure of, ii. 237, 238 Trochus zizyphinus, palate of, ii. 237 Truffle, structure and habitat of the, i. 292, 293 modes of tracing them, i. 293 the red, of Bath, i. 268 Trypethelium Sprengelii, pustules and sporidia of, i. 299 Tuberacei, characters and habitat of the order, i. 292 Tubicola, structure of, ii. 153 found in all seas, ii. 161 Tubipora, characters of the family of, ii. 129