Adaptations of Fishes 189 



Entirely different are the photophores in the midshipman 

 or singing-fish {Porichthys), a genus of toad-fishes or Batra- 

 choididcr. This species Hves near the shore and the luminous 

 spots are outgrowths from pores of the lateral line. 



In one of the anglers (Corynolopliiis rciiihardti) the complex 

 bait is said to be luminous, and luminous areas are said to 

 occur on the belly of a very small shark of the deep seas of 





a d 



Fig. 144. — Etmopterus hicifer Jordan and Snyder. Mi aki, Japan. 



Japan (Etmoptenis lucifer). This phenomenon is now the sub- 

 ject of study by one of the numerous pupils of Dr. Mitsukuri. 

 The structures in CorynolopJiiis are practically unknown. 



Photophores in Iniomous Fishes. — In the Inioini the luminous 

 organs have been the subject of an elaborate paper by Dr. 

 R. von Lendenfeld (Deep-sea Fishes of the Challenger. Ap- 

 pendix B). These he divides into ocellar organs of regular 

 form or luminous spots, and irregular glandular organs or 

 luminous areas. The ocellar spots may be on the scales 

 of the lateral line or on other definite areas. They may be 

 raised above the surface or sunk below it. They may be simple, 

 with or without black pigment, or they may have within them 

 a reflecting surface. They are best shown in the MyctopJiidcc 

 and StomiatidcB, but are found in numerous other families in 

 nearly all soft-rayed fishes of the deep sea. 



The glandular areas may be placed on the lower jaw, on the 

 barbels, under the gill cover, on the suborbital or preorbital, 

 on the tail, or they may be irregularly scattered. Those about 

 the eye have usually the reflecting membrane. 



In all these structures, according to Dr. von Lendenfeld, the 

 whole or part of the organ is glandular. The glandular part 

 is at the base and the other structures are added distally. The 

 primitive organ was a gland which produced luminous slime. 



