42 SALT-WATER FISHES 



quence of predatory habits ; but the explanation lies rather in 

 the fact that the post-larval stages of even vegetable-feeders 

 among fishes live by chasing and devouring tiny living 

 creatures so minute that only the high-power microscope 

 reveals them to the human eye. 



The eggs of fishes show considerable variation in both size 

 and shape. As a general rule, the bony fishes lay round eggs, 

 but that of the anchovy (^Etigrau/is) is oval, and that of the 

 garfish (Belone) has long filaments which serve as anchor- 

 ropes, like the tendrils on the egg-cases of the spotted dog-fish. 

 The anchovy's egg, unlike that of the allied herring, floats in 

 the water, but that of the gar-fish probably sinks, the filaments 

 securing it to weed-clumps or other convenient rests. 



Attempts have with praiseworthy ingenuity been made to 

 trace the influence of a floating or demersal egg on the after- 

 history of the fish hatched from it, but these have signally 

 failed, as may be shown by a few familiar examples of both. 

 The most striking contradictions are, perhaps, the herring 

 (Clupea) and angler-fish (Lop/iius). The herring, hatched 

 from a sinking egg, which develops at the bottom of the 

 sea, spends most of its after-life swimming at the surface. 

 The angler-fish, on the other hand, which emerged from a 

 floating egg, lives when older on the ground, there lying in 

 wait for its victims. It has also been suggested that fishes 

 hatched from pelagic, or floating, eggs are less given to 

 wandering in after-life, since the species is already dispersed 

 in the egg stage. Obviously, the heavy, clinging eggs of the 

 herring, hatching out as they do close to the spot in which 

 they were in the first instance deposited, must tend to restrict 

 the distribution of that fish. On the other hand, the eggs of 

 the mackerel (Scoml^er), which float hither and thither on the 

 surface and are dispersed by every normal current or inci- 

 dental storm, must carry that fish over wider areas. Yet who 

 would care to describe the mackerel as less of a traveller in 

 after-life than the herring .'' The flat-fish have also been 



