PLATE 2 



EXPLANATION OF FIGURES 



7 Reconstruction, based upon sections figured at 1, 2, 3, and 4. Right aspect 

 of right pit. GC, gland cell with its nucleus; GP, pores of gland cell; M, muscles 

 of pit; A^, nerve of ciliated pit; f/ indicates the approximate level or plane of sec- 

 tion shown in figure 5. X 2000. 



8 Transverse section through dorsal ganglion, DGL. X, dorsal ganglion 

 cells; Ph, wall of pharyngeal sheath; Mes, cells of mesenchyme; NVC, nucleus of 

 visual cell; C, lateral cytoplasm of visual cell; L, lens-like cytoi^lasmic region of 

 visual cell; Rh, cone-shaped rhabdome of visual cell ; NAC, nucleus of accessory, 

 ])igmented cell of e.ye; Pg, region of laminated cytoplasm of accessory cell, 

 wliich carries the pigment. X 1500. 



176 



