106 LIVING LIGHTS. 



of whales and other cetaceans ; but the wondrous displays 

 which they undoubtedly produce as they rise, perhaps to 

 escape the ferocious attacks of the killer, are due only to the 

 myriads of small light-givers, — medusce, salpce, crustaceans, 

 and others, — ; which when disturbed become luminous. 



Among the well-known phosphorescent fishes, the Seopelus, 

 found in the greater depths, rises at times, at night, to the 

 surface. Seopelus humboldtii (Plate X., Fig. 1), has a double 

 row of luminous spots on each side of the abdomen. One 

 of the spots, enlarged in reflected light, is shown in the same 

 plate. 



The phosphorescence of Myctophum crenulare, an ally of 

 Seopelus, has been observed ; and, at least on the Pacific 

 coast, this little fish probably rises to the surface, a speci- 

 men an inch and a half in length having been taken from 

 the stomach of an albicore (^Oreynus alalonga) in the Santa 

 Barbara Channel. In this specimen a phosphorescent spot 

 was seen on each mandible near the symphysis, thirty-three 

 along the abdomen, six in front of the ventral fins, six more 

 between the latter and the origin of the anal, and twenty- 

 one between the front of the anal fin and the base of the 

 tail ; quite enough, if all are luminous, to outline the little 

 creature in lines of vivid brightness. 



The long, arrow-like gars are peculiarly surface forms, it 

 being evidently only with extreme difficulty that they leave 

 the surface. Allied to them is Hemiramphus, in which the 

 lower jaw only is elongated ; and, according to Giinther, this 

 interesting fish has a gleaming phosphorescent pustule at the 

 tip of its tail, a circumstance that makes it one, not only of 

 the most unique of the surface forms, but of all the finny 

 light-bearers. Many other forms known to possess luminous 



