PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 229 



fins, the short peduncles of the latter, the conformation of the teeth, 

 the black color, the number of branch iostegal rays (6) as well as of the 

 rays of the anal (4) and caudal (0), and the half-spongy consistence of 

 the skeleton are also, apparently, characters common to all the [known] 

 genera." 



Auother character shared in common by all the species, and at least 

 as noteworthy as several of those thus enumerated by Dr Liitken, is the 

 differentiation in the color of the extremity of the bulbiform termination 

 of the cephalic spine. In all the known species (unless Melanocehis 

 may be excepted), the apical portion or elements of the bulb are of a 

 grayish or whitish color, and thereby quite abruptly differentiated from 

 the rest of the spine, which is of a black color. Some special significance 

 is probably inherent in this characteristic, and it is quite possible, if not 

 probable, that the difference of color is expressive of a differentiation in 

 histological structure, and that the grayish portions are phosphorescent. 

 When the complicated " angling" apparatus of the fishes of this group 

 is considered, it will be thought not unlikely that their power of attrac- 

 tion should be enhanced by a luminosity which may excite the attention 

 or curiosity of their prey, and still more strongly tempt them within the 

 easy reach of their capacious mouths. It is certainly scarcely likely 

 that the characteristic in question, manifested as it is in such widely 

 diverse types, should be a simple immaterial color feature, destitute of 

 other significance. The not few pelagic and deep-sea animals that ex- 

 hibit phosphorescence enhance the probability of the attribute suggested. 

 The verity of the suggestion must, however, be established by histo- 

 logical and physiological data. It can only now be assumed that there 

 is a teleological import in the differentiation of color, and that it is more 

 probable that the whitish area has a phosphorescent property than that 

 it simply serves as a relief for the filaments of the bulb. Especially is 

 this more probable in view of the great depths which the species in- 

 habit, and the consequently limited quantity of light which they enjoy. 

 That the provision, whatever it may be, is an effective one, is apparent 

 from the variety of the forms already discovered, and it seems probable 

 that the family is not only quite characteristic of, but well represented 

 in, the depths of the ocean. 



As to Melanocetus, it is simply said, by Dr. Guntker, to have the ce- 

 phalic filament "more than half as high as the head, and dilated into a 

 small lamella at its extremity". The " lamelliform" character of the 

 dilatation at least requires confirmation, and it is not very unlikely 

 that the dilatation will be found not to be thin or compressed to such an 

 extent as to be entitled to the designation of M lamella", and that the ex- 

 tremity will be ascertained to be whitish. The mode of articulation of 

 the cephalic spine also requires investigation. Dr. Liitken has corrected 

 Dr. Gunther's error of mistaking pharyngeal teeth for palatine and 

 pterygoid, but has not elucidated the points indicated. 

 The several recognized genera are mostly widely differentiated, 



