96 WILLIAM PATTEN. 



Fig. 61. — Diagram of a spider's brain, sbowing relation of the ocelli to the 

 brain-segments. 

 Fig. 62. — Brain of a Myriapod (lulus). 



Fig. 63. — Cross-section of parietal eye, just after hatching (early trilobite 

 stage); depigmented, X 265. 



Figs. 64 — 70. — Series of cross-sections of the parietal eye, after first larval 

 moult (trilobite stage) ; not depigmented. 



Fig. 64:. Section through about the middle of the endo-and ecto-parietal 



eyes. X 265. 

 Fig. 65. Section through the root of the eye, showing the four nerves. 



X 570. 

 Fig. 66. Section of parietal eye-stalk just below the eye. X 570. 

 Fig. 67. Section shows the primitive roots to the parietal eye-nerve 



separating from the epiphysis, x 570. 

 Fig. 68. Section of the epiphysis just below the preceding section. 



X 570. 

 Fig. 69. Section through the base of same. X 570. 

 Fig. 70. Section through the base of the epiphysis, showing its union 

 with the transverse tube, and the communication of the cavities in the 

 same. X 570. 

 Fig. 71. — Cross-section through the base of one of the legs, showing the 

 developing sense organs, nerves, and ganglia in the inner and outer man- 

 dibles. Trilobite stage. X 265. 



Fig. 72. — Section of same in an embryo just after the shedding of the 

 chorion. X 265. 

 Fig. 73. — Same just before hatching, x 87. 



Fig. 74. — Parietal eyes of a Limulus about 3 inches long. The eyes have 

 been dissected away from the cuticle and surrounding connective tissue, 

 mounted in glycerine and viewed from above, x 38. 



Fig. 75.— Three sensory hairs from the cepbalo-thoracic shield of Limulus 

 just after the trilobite stage. Their position and relation to the adult sensory 

 hairs were not determined. 

 Fig. 76. — Sensory bud from thorax of same stage. 



