ALEPOCEPHALOIDS. 283 



ALEPOCEPHALOIDS. 



This group contains tlie family Alepocephalidce and several tj-pes, Ronde- 

 letia, Anomalopterus and Cetoniimus, of questionable relationships to the 

 family and to one another, probably representing different families, but placed 

 here until more is known about them. Approximately the ascertained horizon- 

 tal distribution of the Alepocephalidtc extends in the Atlantic, including the 

 Mediterranean, from ten degrees of south to fifty degrees of north latitude, 

 in the Pacific from the equator northward forty-eight degrees, and in the 

 Indian Ocean from Australia northward. The least depth that has been 

 reported for any of the species is 200 fathoms and the greatest is 2949. 

 The greatest range for an individual species is that of Ak])ocej)/iahis rostmtus 

 Risso, off the north African coasts, from data secured by expeditions sent 

 out b}^ the French government ; this species was taken at various stations 

 between a depth of 453 fathoms and one of 1998, a vertical range of 1545 

 fathoms. Between Japan and Australia the "Challenger" researches 

 gave the family a range extending from a depth of 345 to one of 2150 

 fathoms; and in the northern portions of the Indian Ocean the " Investiga- 

 tor" secured specimens at various depths, from 240 down to 1000 fathoms. 



There is less micertainty regarding the habitat of this family than in 

 respect to that of some of the others. Structure, blackness of integument, 

 food, and the condition of the specimens on arrival at the surface all favor 

 the conclusion that these fishes dwell close to the bottom, hundreds of 

 fathoms below the surface. The large eye is a distinguishing feature of the 

 AlepocejDhalidoj and its possession must be regarded as proof of the presence 

 of light either in the bodies of the other inhabitants of the sea bottom, 

 fellows, enemies, prey, etc., or in the medium in which the family lives, one 

 or the other or both. In the absence of luminous organs, except, it may be, 

 in Xenodermichthys, the principal dependence for recognition of others of 

 the same species at a distance, probably lies in ability to recognize similarities 

 and differences in form, outlines, positions of fins, and the like, and these are 

 made visible by the luminosity of the integuments of the object or by the light 

 in the water around it, presumptively by both of them. The surfaces of these 

 fishes are more or less phosphorescent, but aside from this it would appear 

 that the large eye, with the lack of special light organs and of special devel- 

 opments of the organs of touch, should be taken as evidence that the Alepo- 



