PRODUCTION OF LIGHT 419 



it bears a luminous organ. Of Linophryne lucifer only a single 

 specimen is known, which was picked up at the surface near 

 Madeira by a sea-captain ; it had swallowed a fish larger than 

 itself: in this remarkable fish the cephalic tentacle is short and 

 thick, black in colour and enlarged at its end into an ovate bulb 

 the outer half of which is white and probably luminous. There 

 can be no doubt that this fish naturally lives at the bottom in 

 considerable depths ; it has enormously long teeth and a long 

 barbel below the chin. In Caidophryne jordani, taken in the 

 Atlantic at 1200 fathoms, there is no luminous organ on the 

 cephalic tentacle but numerous short luminous filaments scat- 

 tered over the head and body ; the second dorsal and ventral 

 fins are much elongated and also the caudal fin. 



In the genus Poriclithys of the family Batrachidae which is 

 intermediate between Blennies and Anglers, the skin, which is 

 scaleless, bears numerous series of small spots ; these have been 

 supposed to be pores of the dermal canal system, but it has 

 been proved that on the body there are no sensory canals 

 present, the sense-organs of the lateral line system being on the 

 free surface of the skin. Some of the small spots are sense- 

 organs of this kind, similar to those which occur in most fishes 

 within the lateral canal, and consisting of little buds of epider- 

 mic cells connected with branches of the sensory nerves, while 

 others have an entirely different structure, a structure which re- 

 sembles that of phosphorescent organs. PoricJitJiys notatus oc- 

 curs abundantly along the Pacific coast of North America from 

 Sitka to Panama. It is caught in spring and summer between 

 tide-marks or in shallow water, where it comes to spawn. Its 

 eggs are cemented in a single layer to the under surface of 

 stones, and the male guards them, and takes care of the young 

 brood until they are an inch in length. In surface view the 

 phosphorescent organs appear as bright silvery spots or beads 

 in the general brown coloration, the average number is 350 on 

 each side of the body. Some of the lines of spots consist of 

 phosphorescent organs only, in others these are associated with 

 sense-organs, usually one phosphorescent organ being placed 

 above, and one below each sense-organ. Mr. Greene kept 

 specimens of the toadfish, as it is locally called, in aquaria and 

 observed it carefully in the dark, both when it was quiet and 

 when violently excited, but never saw any ohosphorescence, 



