5 18 THE ORIGIN OF VERTEBRATES 



Ammoccetes, epithelial cells of skin, 347 



pits, 173, 200 

 eye, 93 

 ,, „ muscles, 267 



,, median or pineal, 63, 75, 76, 77, 78, SO, 85, 86 

 „ left, 78, 79 

 fat-column, 181, 182 

 ,, „ in degenerated muco-cartilage, 333, 334 



„ ganglia in embryo, 229, 283 



gland-tissue round the brain, 209, 210, 379 

 head-region, 128, 162, 163, 193, 293, 294, 296, 298, 335 

 head-shield, 329, 331, 338 

 liver, 442, 452 



lymphatic glandular tissue, 426 

 „ Mvillerian fibres, 489 



,, muscles, eye, 173, 267 



,, ,, lip, lower, 297 



„ „ upper, 305 



,, respiratory, 171 



somatic, 332, 336, 409 

 tubular, 173, 298, 309 

 ,, nerves, cranial, 141 



facial, 186, 311 

 ,. „ glossopharyngeal, 186 



,, ,, optic, 105 



trigeminal, 232, 288, 288 

 vagus, 153, 173, 186 

 nerve-fibres, medullation of, 20 

 notochord, 182, 435 

 olfactory tube, 219, 225, 227, 317 

 oral chamber, 317, 243, 287, 458 

 parasitism, 60, 286 

 pituitary, 321 

 ,, prosomatic region, 243 



,, pronephric duct, 402, 405 



relationship to Ostracodermata, 326, 338, 344, 414, 416 

 ,, retina, 93, 111 



skin, 58, 346, 348, 442 

 skeleton, 125, 126, 132, 291, 296, 335 

 ,, segments, comparison with segments of Eurypterus, 323 



„ „ facial, 201 



hyoid, 186, 201 

 „ „ prosomatic, 286 



,, septa between myomeres, 416 



„ tentacles of upper lip, 303 



,, test, biological, to show relationship with Limulus, 493 



thyroid, 192, 194, 196, 205, 213, 430 

 transformation, 18, 59, 125, 168, 193, 199, 200, 220, 227, 228, 287, 291, 



304, 307, 309, 331, 336, 347, 349, 389, 445 

 velum, 228, 289, 298, 302 

 Amcebocytes, 473 

 Amphibia, 23, 345 



