PLATE LXXI. 



Pachystoinias microdon. 



Fig. 25. Head in profile, natural size, drawn from a spirit specimen. 



ft, Anterior suborbital phosphorescent organ ; h, posterior suborbital phosphorescent 

 organ. 



Fig. 26. Suborbital phosphorescent organs in situ, x 2. 



a, Anterior ; h, posterior suborbital phosphorescent organ. 



Fig. 27. Vertical section of the anterior suborbital phosphorescent organ. x 20. 



a. Pigment coat ; b, reticulate gland ; c, layer of light-reflecting spicules ; d, radial 

 gland-tubes ; e, outer skin, the margins of which can be drawn some distance over 

 the surface of the phosphorescent organ. 



Fig. 28. Vertical section of the posterior suborbital phosphorescent organ. x 25. 



a. Granular outer surface; h, nervus phosphorius ; c, layer of light-reflecting 

 spicules ; d, radial gland-tubes ; <?, outer skin, the margins of which can be drawn 

 some distance over the jihosphorescent organ. 



Fig. 29. Anterior suborbital phosphorescent organ. x 50. 



Light-reflecting layer of spicules seen from the surface. The external reticulate part of 

 the gland communicates by these oval holes with the internal radial jiart. 



Fig. 30. Section of the anterior suborbital organ shown in fig. 27. x 350. 

 a, Pigmented partition-membranes ; h, gland-tubes. 



Fig. 31. Section of the posterior suborbital phosphorescent organ sho\vn in fiw. 

 28. X 200. 



n, Nervus phosphorius ; /<, light^reflecting layer of spicules traversed by numerous 

 nerves and blood-vessels ; c, termini of the radial glaud-tubes; a, thick partition 

 "membranes with nerves and blood-vessel ; /3, glaud-tubes. 



Fig. 32. Longitudinal section of a compound phosphorescent organ from the 

 lateral row. x 40. 



Fig. 33. Section of the compound phosphorescent organ shown in fig. 32. 

 X 400. 



rt, Pigment coat; b, light-reflecting membrane; <•, granular layer with large cells in it 

 (ganglion cells); d, radial gland-tube.s. 



