_renardi_ (_Vipera_), 227 Replacement teeth, 55 Reproduction, 82 Reptation, 93 _Reptilia_, 1 _Rhiptoglossa_, 1 _riccioli_ (_Coluber_), 202 Ring-Snake, 152 _romanus_ (_Coluber longissimus_, var.), 188 _rubens_ (_Coluber_), 204 _rubro-maculosus_ (_Tropidonotus tessellatus_, var.), 162 Rustling, 102 Sand-Boa, 147 Sand-Snakes, 91 Sand-Viper, 249 _sardus_ (_Zamenis_), 172 _sauromates_ (_Coluber_), 183 _scalaris_ (_Coluber_), 194 _scalaris_ (_Coronella austriaca_, var.), 199 Scales, 14 _schwoederi_ (_Coluber leopardinus_, var.), 193 _scutatus_ (_Tropidonotus natrix_, var.), 155 _semimaculata_ (_Contia modesta_, var.), 207 Sense organs, 73 _seoanei_ (_Vipera berus_, var.), 235 Serotherapy, 66, 134 Serum treatment, 67 Shedding of the epidermis, 20 Shields, 14 Sixth sense, 75 Skeleton, 40 Skull, 40 Smallest Snakes, 21 Smooth Snake, 197 Snake-charmers, 139 Snake-stones, 141 Snake swallowing her young, 88 Snake-worship, 139 Snout, 12 Solenoglyphs, 56 Southern Smooth Snake, 202 _Squamata_, 1 _steindachneri_ (_Vipera ammodytes_, var.), 252 Stomach, 79 Subcaudal shields, 15 _subfasciatus_ (_Tropidonotus natrix_, var.), 155 _subgriseus_ (_Coluber longissimus_, var.), 189 _Symoliophis_, 7 Syncranterians, 58 Tail, 9 _Tarbophis_, 216 _Tarbophis fallax_, 217 _Tarbophis iberus_, 219 Teeth, 53 Tessellated Water-Snake, 160 _tessellatus_ (_Tropidonotus_), 160 Thymus gland, 78 Ticks, 108 Tongue, 74 Tongue-worms, 108 _torquatus_ (_Coluber_), 152 _trabalis_ (_Zamenis gemonensis_, var.), 172 Trachea, 78 _transcaucasiana_ (_Vipera ammodytes_, var.), 256 Tree-Snakes, 36, 92, 94 Trematoda, 112 _Tropidonotus_, 152 _Tropidonotus chersoides_, 167 _Tropidonotus natrix_, 152 _Tropidonotus tessellatus_, 160 _Tropidonotus viperinus_, 165 _Typhlopidæ_, 4, 143 _Typhlops_, 144 _Typhlops vermicularis_, 144 Ureters, 81 _Uropeltidæ_, 5 Urosteges, 15 _ursinii_ (_Vipera_), 221 Veins, 77 _veithi_ (_Coronella austriaca_, var.), 199 Ventral shields, 15 _vermicularis_ (_Typhlops_), 144 Vertebræ, 50 Vertebral column, 50 _Vipera_, 221 _Vipera ammodytes_, 249 _Vipera aspis_, 239 _Vipera berus_, 230 _Vipera latastii_, 247 _Vipera lebetina_, 257 _Vipera macrops_, 224 _Vipera prester_, 235 _Vipera renardi_, 227 _Vipera ursinii_, 221 _Viperidæ_, 5, 220 _Viperinæ_, 5, 220 Viperine Water-Snake, 165