Sargent. — Optic lleriex Apparatus. 



PLATE 9. 



Fig. 62. Piiralichtliys donfatiis, adult. Tnuisverse section of the nipsencephalon 

 and torus loiigitu<linalis through the posterior coiiiniissure. X 15- 



Fig. (iS. Cynoscion regalis, adult, section as above. X 15. 



Fig. 04. jVniblyopsis spelaeus, adult. Transverse section of the roof of the mesen- 

 cephalon and torus longitudihalis, caudad of the jio.sterior commissure. 

 X 40. 



Fig. 05. AtiK'iurus nebulosus, adult, section as above. X 40. 



Fig. 06. Pseudoplouronectes aniericana, adult. Sagittal section through the (,'analis 

 centralis, in the middle portion of the cord, showing the branching of 

 Keissner's fibre. Anterior is npjterinost and ventral at the left. X 1000. 



Fig. 67. Squalus acanthias, embryo, 10 mm. long. Sagittal section througli the 

 ])()sterior ])ortion of the c-analis centralis, showing two of the postiTior 

 canal-cells, and some of the line branches entering the ventral wall of 

 the canal. X 1350. 



