Duck, _41_, 334; beak, 329; claws, 330; cranium, =313=; exoskeleton, 302; pectoral girdle, 321; pelvic girdle, 324, =311=, =325=; pes, 327; posterior limb, 326; ribs, 320; skull, 312, =312=, =313=; sternum, 321; vertebral column, 307; wing, 322, =304=, =305= Duckbill, _43_; see _Ornithorhynchus_ Dugong, _44_; humerus, 501; pelvis, 514; thoraco-lumbar vertebrae, 448; see _Halicore_ Duplicidentata, _48_, 366; dental formula, 435; skull, 478 Eagles, 335 Eared Seals, _369_; scapula, 498; see Otariidae _Echidna_, _43_; caudal vertebrae, 453; manus, 504; pelvis, 513; sacral vertebrae, 451; shoulder-girdle and sternum, =494=; skull, 455; spines, 417; spur, 418; thoraco-lumbar vertebrae, 447 Echidnidae, _43_; pes, 521 Ectethmoid, 21 n. Ectocondylar ridge, dog, 406 Edentata, _43_; auditory ossicles, 487; arm bones, 500; caudal vertebrae, 453; cervical vertebrae, 443; manus, 504; pectoral girdle, 495; pes, 522; pelvis, 513; ribs, 491; sacrum, 452; skull, 457; sternum, 489; teeth, 424; thigh and shin, 517; thoraco-lumbar vertebrae, 447 Eel, _33_; scales, 105 Elasmobranchii, _31_; cranium, 118 f.; clasper, 132; general characters, 61; pelvic fins, 131; ribs, 125; teeth, 109; vertebral column, 113 f.; visceral arches, 120 _Elasmotherium_, _46_; mesethmoid, 470 Elephant, _47_; auditory ossicles, 487; caudal vertebrae, 453; ribs, 491; skull, 473 f., =474= and =475=; tusks, 420; see also Proboscidea Elephantidae, _47_ _Elephas_, _47_, _364_; dental formula, 434; _E. planifrons_, 435; see Elephant _Elginia_, _36_; skull, 191, 283 Embolomerous, 172 Emeu, _40_, _299_; aftershaft, 328; claws, 330 Enamel, 4; -- cap, 7; -- organ, 7 Endochondral ossification, 11 Endoskeleton, Amphibia, 170; birds, 331 f.; cod, 83 f.; crocodile 239, f.; dog, 377 f.; dogfish, 71 f.; duck, 306 f.; fish, 112 f.; frog, 151 f.; mammals, 442 f.; newt, 138 f.; reptiles, 275 f.; turtle, 218 f. Engystomatidae, _36_ Entoplastron, turtle, 217 Epanorthidae, _43_, _350_ Epi-branchial, cod, 101; dogfish, 78; salmon, 94 Epicoracoid, 25; frog, 163; turtle, 232; Monotremes, 493; vestiges of in Rodentia, 497 _Epicrium_, _35_; orbit, 179 Epidermal exoskeleton, birds, 328; crocodile, 237; dog, 374; duck, 302; mammals, 416; reptiles, 270; turtle, 214