PELAGIC FISHES. 293 



of swimming is greatly reduced, as in Antefinarius, Hi;ppo- 

 campus, and Gymnodonts ; they frequent places in the ocean 

 covered with floating seaweed, or drift on the surface without 

 resistance, at the mercy of wind and current. The Echeneis or 

 Sucking-fishes attach themselves to other large fish, ships, or 

 floating objects, and allow themselves to be carried about, 

 unless change of climate or want of food obliges them to 

 abandon their temporary carrier. Finally, another class of 

 Pelagic fishes come to the surface of the ocean during the 

 night only; in the day time they descend to some depth, 

 where they are undisturbed by the rays of the sun or 

 the agitation of the surface-water : such are Brama, the Ster- 

 noptychidce, Scopelus, Astronesthes ; fishes, the majority of 

 which are provided with those extraordinary luminary organs 

 that we find so much developed in the true Deep-sea fishes. 

 Indeed, this last kind of Pelagic fishes forms a passage to the 

 Deep-sea forms. 



Pelagic fishes, like shore fishes, are most numerous in the 

 Tropical Zone ; and, with few exceptions (Uchinorhinus, Psenes, 

 Sternoptychidce, Astronesthes), the same genera are repre- 

 sented in the tropical Atlantic as well as in the Indo-Pacific. 

 The number of identical species occurring in both these 

 oceans is great, and probably stUl greater than would appear 

 from systematic lists, in which there are retained many specific 

 names that were given at a time when species were believed 

 to have a very limited range. The Pelagic fauna of the 

 tropics gradually passes into that of the temperate zones, 

 only a few genera, like Cyhivm, Psems, Antennarius, being 

 almost entirely confined to the tropics. All the other tropi- 

 cal genera range into the temperate zones, but their repre- 

 sentatives become scarcer with the increasing distance from 

 the equator. North of 40° lat. IST. many genera have disap- 

 peared, or are met with in isolated examples only, as Carcha- 

 rias, Zygcena, Notidanus, Myliohatidw, Badylopterus, Echeneis, 



