53° THE ORIGIN OF VERTEBRATES 



Nerves, of prosoma in Limulus, 235, 355 

 ,, regeneration of, 469 

 ,, roots, of Limulus, 157 

 ,, sacral, 448 

 ,, segmental, 152, 156 

 ,, segmental nature of cranial, 259, 411 

 ,, spinal, absence of lateral roots in, 388 

 ,, spinal accessory, 154 



trigeminal, 151, 155, 156, 234, 243, 257, 279 

 „ motor nucleus of, 280 



,, ,, of Ammoccetes, 288 



tripartite arrangement of cranial nerves, 154, 157, 235, 267, 355 

 trochlear, 48, 155, 234, 263, 276 

 vagus, 151, 154, 156, 173, 186, 356, 447, 449 

 Nervous system, central, comparison of Vertebrate and Arthropod, 36, 457 



,, ,, connection of, with muscular and epithelial tissues, 464 



,, „ ,, with retina, 71 



„ „ disease of, 50 



„ „ evidence of, 8 



„ ,, evolution of, 34 



,, ,, importance of, 16, 463, 482, 498 



,, ,, invertebrate, 10, 13, 54 



,, ,, origin of, 480 



„ ,, relation of germ-band to, 483 



,, ,, segmentation of vertebrate, 51 



tube of, 36-51, 102, 211, 433, 455, 457 

 vertebrate, 10, 13, 40, 41, 152 

 ,, enteric, 447 



sympathetic, 2, 424, 428, 448, 491 

 Neurenteric canal, 37 

 Neuroblast, 465 



Neuromeres, 55, 247, 262, 312, 316 

 Neurones, 72, 92, 465 

 Neuropil, 71, 91 

 Neuropore, 220, 457 

 Nose, 219 



„ of Osteostraci, 329, 352, 458 

 Notochord, 120, 122, 180, 181, 220, 244, 295, 318, 405, 417, 433, 436, 494 



Ocelli, 70 



(Esophagus of Ammoccetes, 405 



,, Arthropod, compared to tube of infundibulum, 4, 244, 440 



Olfactory apparatus, evidence of the, 218 

 ,, organs of the Scorpion group, 220 



tube of Ammoccetes, 219, 225, 244, 317 

 Oligochseta, 421, 478 

 Operculum of Eurypterus, 191, 212, 291 

 Limulus, 189, 202, 235, 295 

 ,, Phrynus, 191 



Scorpion, 189, 206, 212, 372 

 Thelyphonus, 189, 190, 206 

 Organs, arrangement of, 10 



