526 THE ORIGIN OF VERTEBRATES 
Germ-cells, 471 
Giant-fibres, 489 
Gigantostraca, 25, 234 
Gills, 148, 161, 185, 214, 494 
Glabellum, 339 
Glands, carotid, 427 
»  cCoxal, 242, 246, 319, 821, 425, 429 
»  uctless, 418 
» generative, of Limulus, 209 
» internal secretion of, 214 
» lymphatic, 418 
» pineal, 15, 63, 75, 456 
» pituitary, 244, 246, 319, 425 
» segmental, of Crustacea, 422 
» submaxillary, 466 
59 sweat, 448 
» thymus, 425 
» thyroid, of Ammoceetes, 193, 194, 196, 201, 205, 429 
» tissue round brain of Ammoccetes, 209, 379 
uterine, of Scorpion, 202, 208, 204, 205 
uathostamata, 60, 343 
Goblet, 359, 360, 373 
Goitre, 215 
Gonad, 475, 479 
Gonoccele, 475, 481 
Grooves, ciliated, 188, 197, 212 
»  hyper-pharyngeal of Amphioxus, 410 
55 ventral, of apus and trilobites, 436 
Gymnophiona, 398 
Hamocytss, 472 
Head of embryo dogfish, 121, 123 
Head-shield, dorsal, of Ammoccetes, 330, 331, 338 
. es Auchenaspis, 29, 31, 338 
bs a Cephalaspis, 327, 328, 380, 338, 348 
G ' Cyathaspis, 340 
3 3 Didymaspis, 338 
o - evidence of segmentation, 339 
. 5 Keraspis, 328 
$5 Ostreostraci, 327, 348 
Paleostracan, 348 
i 99 Pteraspis, 29 
a Thyestes, 29, 81, 327, 332, 338, 340, 341, 348 
- venteal, Scaphaspis, 349 
Heart, nerves, 2, 447 
», origin of vertebrate, 179, 451, 459 
» relative position in vertebrate and invertebrate, 175 
», veins forming vertebrate, 180 
Hemiaspis, 24, 25, 249, 250, 351, 414 
Hemispheres, cerebral, 47 
Hepatopancreas of Ammocostes, 452 
5 Limulus, 211 
