Antiarcha, _31_; general characters, 55 Antibrachium, see fore-arm _Antilocapra_, _46_; horns, 417 Antilocapridae, _46_ Antitrochanter, duck, 325 Antlers, 8, 358; Cervidae, 469 Antorbital process, 18 Anura, _36_; general characters, 136; hyoid apparatus, 180; pelvis, 187; posterior limb, 188; skull, 179; sternum, 182; vertebrae, 172 _Apatornis_, _40_; vertebrae, 332 Apteria, 328 Apteryges, _40_ _Apteryx_, _40_, _299_; aftershaft, 329; anterior nares, 333; claws, 330; foot, 342; manus, 338; pectineal process, 341; pectoral girdle, 338; pneumaticity of skeleton, 331; _A. oweni_, pelvic girdle and sacrum, =340= Aqueductus vestibuli, dogfish, 74 Arcade: infratemporal--, crocodile, 255; _Sphenodon_, 283; inner --, duck, 318; outer --, duck, 318; supratemporal --, crocodile, 257; reptiles, 281 Archaeoceti, _44_; general characters, 356; skull, 461; teeth, 426 _Archaeopteryx_, _40_, _297_; claws, 330; fibula, 341; mandible, 335; metatarsals, 342; pelvis, 341; ribs, 336; sacrum, 333; skull, 333; tail, 333; teeth, 330; wing, 338 Archaeornithes, _40_; characters, 297 _Archegosaurus_, _35_, _136_; palatines, 177 Archipterygium, _Ceratodus_, 127; Ichthyotomi, 62 Arcifera, _36_, 185 Arctoidea, _48_, 369; teeth, 438 _Ardea_, _41_; see Heron Ardeae, _41_ Arm, see fore-arm and upper arm Armadillo, _44_, _352_; cervical vertebrae, 443; femur, 517; humerus, 501; lumbar vertebrae, 447; manus, 505; pectoral girdle, 495; pelvis, 513; ribs, 491; sacrum, 452; scales, 417; scutes, 419; skull, 459; teeth, 424 Armour plates, 8 Arthrodira, _34_; characters, 70 Articular, 22; cod, 100; crocodile, 258; duck, 319; newt, 144; salmon, 94; turtle, 231 Artiodactyla, _45_; characters, 358; manus, 506; odontoid process, 445; pes, 522; ribs, 491; skull, 465; teeth, 427; thoraco-lumbar vertebrae, 448 Asses, _360_ _Asterolepis_, _31_, _55_ Asterospondyli, 114 Astragalus, 27; crocodile, 268; dog, 414; mammals, 521 Astrapotheriidae, _46_ _Astrapotherium_, _46_, 361; dental formula, 432; femur, 519; pes, 525 _Ateles_, _49_; pollex, 512; tail, 454 Atlantosauridae, _38_ Atlas, 15; crocodile, 240; dog, =379=, 380; duck, 309; ox, =445=; turtle, 219 Attachment of teeth, 4; in fish, 107 _Auchenia_, _45_; see Llama