GADOIDS. 179 



The amount of specializing modification undergone by bathybial Gadoids 

 is less comparatively than that seen in groups like the Pediculates or even 

 the Brotuloids. Special light producing organs have not yet been discov- 

 ered ; though probably the lateral system is more or less luminous in a 

 number of the genera. No species deprived of sight are known as yet; the 

 eye generally is large and well developed. Such modifications as exist are 

 most apparent in the lateral system and in its surroundings on the skull, 

 where the changes do not differ in any noticeable extent or character from 

 those obtaining on most other deep sea fishes, except jierhaps in case of 

 Fhycis rcgius Walb., on which the aural and the occipital portions of the 

 system are considerably differentiated, in connection with electric functions, 

 this being the species capable of giving off a very perceptible discharge as 

 recorded by Prof. A. Agassiz, 1888, in the Three Cruises of the "Blake," II., 

 p. 23. The system in this species and others of the group has been worked 

 out as far as was possible from the alcoholic specimens and is figured on 

 Plate LXXXI. fig. 2, Plate LXXXIL, and Plate LXXXIII. fig. 1. Fila- 

 mentary developments no doubt serving as tactile organs occur on many 

 species, but neither in such extent nor condition as should serve to separate 

 the Gadoid much from other deep sea forms, or, for that matter, from 

 various pelagic or shoal water species. 



The specimens in this collection were generally taken from localities in 

 ■which the bottom was muddy and in temperatures the average of which is 

 about 48.2 degrees Fahrenheit, or of which the recorded extremes were 

 57.3 degrees and 36.8. The greatest range noted for a single species is that 

 of Plii/cicnhis longipes, 56.2 to 39 degrees, which species ranged vertically 

 from the 127th fathom to the 695th. This range in depth is much ex- 

 ceeded in the group by species of the northwestern Atlantic, Antimora viola 

 G. B., from a depth of 306 to one of 1434 fathoms and Lccmonema melanurum 

 G. B., taken at a depth of 208 fathoms and downward to that of 1437, which 

 gives these species vertical ranges of 1128 and 1259 fathoms respectively, 

 the greatest in the family and each more than a mile. In the case of these 

 fishes as in that of others it is very evident that of the two, temperature 

 and pressure, it is temperature and not pressure that is the determining 

 factor in vertical distribution. This is shown by Antimora viola captured 

 by the steamer " Albatross " at some thirty different stations for which 

 both depth and temperature of the bottom are given. The depths vary 

 more than a thousand fathoms while the temperatures corresponding to 



