Sabgent. — optic Reflex Apparatus. 



PLATE 8. 



Fig. 55. Tantogolabrus adspersus, larva, 2 cm. long. Parasagittal section through 

 the anterior portion of the torus and posterior commissure, somewhat 

 oblique, tlie lower portion of the figure being more nearly median than 

 the upper. X 205. 



Fig. 56. Tautogolabrus adspersus, larva, 25 mm. long. Sagittal section of the ante- 

 rior portion of the torus and posterior commissure. X 205. 



Fig. 57. Tautogolabrusadspersus, young, 15 cm. long. Transverse section through 

 the torus and posterior commissure, the details filled in from three ad- 

 jacent sections. X H7. 



Fig. 58. Menidia notata, adult. Transverse section of the torus longitudinalis and 

 adjacent portions of the tectum opticuni, caudad of the posterior com- 

 missure. X 87. 



Fig. 59. Fundulus heteroclitus, larva, 10 mm. long. Sagittal section of the ante- 

 rior portion of the midbrain roof. X 205. 



Fig. 60. Salvelinus fontinalis, larva, 25 mm. long. Transverse section of the torus 

 longitudinalis and mesal portion of the tectum opticum, just caudad of 

 the posterior commissure. X 205. 



Fig. 61. Ameiurus nebulosus, 15 mm. long. Sagittal section of the posterior por- 

 tion of the cord. The posterior canal-cells are drawn in from two 

 adjacent sections. X 1000. 



