THE FISH OF THE DEEP SEA 163 



barbel is provided with a terminal swelling, shaped 

 like a dumb-bell, which may be capable of emitting a 

 phosphorescent light and serve the animal as a lure 

 for the attraction of its prey. The genus Halacosteus, 

 too, presents us with some of the most remarkable 

 forms that are found in the abysmal zone. The 

 mouth is of enormous size and the integuments of 

 the abdomen present very definite longitudinal folds, 

 leaving no doubt that this fish is able, like several 

 others living in deep water, to swallow prey of an 

 enormous size. 



But a perfectly unique structure in this fish l is 

 a thin cylindrical muscular band which connects 

 the back part of the mandibular symphysis with 

 the hyoid bone. It is probably the honiologue of a 

 muscular band which, in other Stomiatids, stretches 

 on each side from the mandible to the side of the 

 hyoid, the two bands coalescing into an unpaired one in 

 Malacosteits. It is, in the present state of preservation, 

 much elongated, like a barbel, but during life it is 

 notably contractile, and serves to give to the extremity 

 of the mandible the requisite power of resistance 

 when the fish has seized its prey, as without such a 

 contrivance so long and slender a bone would yield to 

 the force of its struggling victim.' 



M 2 



