520 THE ORIGIN OF VERTEBRATES 
Arthropoda, resemblance to ancient fishes, 29 
Astacus, brain, 54 
» digestive ferment in cells lining the carapace, 442 
» optic chiasma, 101 
5, optic stalk, 91 
» retina, 98 
Asterolepis, 326, 342 
Atrium, 410 
Auchenaspis (Thyestes), 30, 31, 75, 275, 326, 327, 328, 338 
Auditory apparatus, 355 
Auerbach, plexus of, 447 
Aurelia, 475 
Autonomic nerves, 3 
BaLanoG Losses, 12, 12, 433, 438, 494 
Bdellostoma, 394, 405 
Belinurus, 24, 249, 351 
Bird, rhomboidal sinus, 46 
Bladder, 449 
» swim, 148 
Blastula, 459, 471, 473 
Blood, 468, 472, 474 
» circulation, in Ammoccetes and Limulus, 174 
», secretion of ductless glands into, 418 
Bothriolepis, 29, 82, 239, 326, 351, 450 
Bone, 344, 474, 481 
Brain, Ammoccetes and Arthropod, 54, 61 
,, and brain-case of Ammoccetes, 40, 41, 46, 209 
» caudal, of Thelyphonus, 450 
» epithelial lining of, 38 
s, roof, 89 
},  Spheroma serratum, 62, 90 
»,  Thelyphonus, 56 
., ventricles, 4 
vesicles, 48 
Sronshisl basket-work of Ammoccetes, 126, 128, 296, 331, 335 
Branchipus, 28 
a brain, 51, 54 
‘i eyes, lateral, 88 
40 s » retina of, 91, 97 
sh > median, 75 
- excretory organs, 396 
i (Artemia) diverticula of gut and retinal ganglion, 110, 111, 113 
95 nerves of appendages, 157 
53 segmentation, 159 
resemblance to Trilobite, 436 
Busiodor, 24, 30, 249, 3441, 351, 414 
Bundle of Meynert, 48, 77 
Bundles, posterior longitudinal, 489 
Buthus, muscles, 270 
CALCIFICATION in aponeuroses of Cephalaspis, 414 
