34 Fishery Board for Scotland. 



It appears, therefore, that Lcphius piscatorius has not only a very wide terri- 

 torial range, but its bathymetric range is also very great. 



The sub-order Pediculati, to which LopJiius belongs, form a group, the members 

 of which are quite easily distinguished from all other forms. Although this group 

 is a very characteristic one, it includes members which are peculiarly adapted for 

 Ufe in very divergent habitats. Some of the members of the order belong exclusively 

 to the deep sea ; others, such as Antennarius, are at home at the surface amongst 

 the sea- weed of the open sea. 



The members of the family Lophiidse are, however, all true bottom forms, which 

 range from moderate to great depths. 



Smith (1892) considers that the fishes of the genus Lophius should really be 

 regarded as shore-fishes, for, at least during youth, they live in shallow water, 

 but, when older, they withdraw to greater depth. Gill (1905) says that, although 

 the Angler is quite common in shallow water, it appears to be at home in deep 

 water, and Giinther, on the strength of its capture in deep waters, has admitted 

 it to his list of deep-water forms. 



The specialised form and the characteristic adaptations of Lophius piscatorius, 

 which have given to the species the name of fishing frog, have been regarded' by 

 most observers as mainly modifications suited for life in the shallow water, the 

 tag-like processes of the skin, and the fishing apparatus having generally been 

 regarded as modifications especially adapted for life in the sea- weed zone. Indeed, 

 this view is the predominant one, and is perhaps largely owing to the graphic 

 description which Saville Kent gave in 1874 of a large Angler which was living in 

 one of the tanks of the Brighton Aquarium. 



Fritsch (1884), however, in his work on the angling apparatus of Lophius, has 

 shown that the Angler is peculiar in possessing a superficial layer of closely-packed 

 ganglion cells on the posterior portion of the medulla, which are in intimate relation 

 with the angling apparatus and the sensory skin system. The observations made 

 by Mr. Lane, which Cunningham (1896) gives, are therefore of peculiar interest. 

 " But another, and perhaps more important use of the tentacle is indicated by some 

 experiments made during the Irish Survey by Mr. Lane, and mentioned in Mr. 

 Holt's Report (Scientific Proc. Royal Dublin Society, vol. III., part IV., p. 459). 

 Mr. Lane found that, when he touched the tip of the erected tentacle with a stick, 

 the fish at once snapped with its jaws, so as to catch exactly that part of the stick 

 which had touched his tentacle. This was repeated until the fish was exhausted. 

 It is evident that this automatic and precise mechanism of sensitive nerve and jaw 

 muscles must be most effective in the capture of the Angler's prey. It is a spring- 

 trap of the most certain action, always set, and never betraying its nature. Any 

 fishes swimming near the ground, are liable to touch the tentacle of the Angler, 

 which cannot be distinguished from the most innocent and insignificant frond of 

 weed or stem of zoophyte, and to touch it is certain and immediate death." 



Such a mechanism, which does not depend on sight, should be as effective for 

 the capture of prey in the deeper waters as on the shallow grounds. 



The Angler has, however, many characters highly suggestive of a deep-water 

 habitat ; the bluish-black colouring of the upper surface, the loose skin with its 

 numerous serous spaces, and the weak development of lime in the skeleton are 

 especially noteworthy. So, too, in the young bottom forms, the abundance of 

 mucoid tissue and serous spaces, are characteristics which must not be overlooked. 



In short, then, Lop)hius 2nscatorius as a species is very closely related to forms 

 which are true inhabitants of the deep waters, but the Angler itself is an inhabitant 

 of more moderate depths, and has extended its range into the shallow waters. 



The Paucity op Recoeds of the Young Stages. 



Lophius piscatorius is, therefore, a species which is very frequently met with 

 in the adult form in waters of moderate depths, both on the European and American 

 sides of the Atlantic. Yet, as previously referred to, the spawn and young stages 

 have only been recorded from isolated localities over this very wide area. No 

 satisfactory explanation has been given for the paucity of records of young forms 

 of such a frequently occurring adult. One must remember, however, that the 

 spawning area of a species is, as a ride, much more restricted than the actual dis- 



