ON LUMINOUS ORGANS OF FISHES. 25 



Explanation of Plate. 



Fig. 1. — Transverse section of the skin from the rostoral region of Etmo- 



pterus hicifer, showing a punctate photophore with closed iris, 



cut longitudinally, x 320. 

 Fiof. 2. — Paratano;ential section of the skin at the level of the iris of a 



punctate photophore from the abdomen of E. frontimaciilatus ; 



iris closed, x 320. 

 Fig. 3. — Transverse section of the skin from the abdominal region of 



E. frontimaculatus, through a punctate photophore with opened 



iris. X 320. 

 Fig. 4. — Another organ from the same section as in fig. 2, passing 



through the level of the opened iris, x 320. 

 Fig. 5. — Photogenic gland-cells from the inner section of a luminous organ 



of Maurolicus pennanti. x 1,000. 

 Fig. 6. — Photogenic gland-cells from the outer section of the same, x 1,000. 

 Fig. 7. — Paratangential section through a lens of a thoracic organ of 



Maurolicus pennanti. x 400. 

 Fig. 8. — Transverse section through a lens of an anteorbital organ of 



Maurolicus pennanti. x 400. 

 Fig. 9. — An anteorbital organ of 3Ii/ctoplum ivatasei, showing a nerve; 



silver impregnation. x 100. 

 Fig. 10. — Photogenic body of an anterior anal organ of 3Iyctophcm 



ivatasei showing a nerve entering it, impregnated with silver. 

 X 320. 

 Fig. 11. — Another section from the same series as the former, x 650. 



g — gelatinous connective tissue. pr — cytoplasmic portion. 



ir — iris. r — reflector. 



/ — lens. sc — secretion product. 



n — nerve. sn — blood sinus. 



nu — nucleus. v — blood vessel. 



pg — pigment layer. vc — vacuole. 



ph — photogenic cell. 



