236 "PERFECT-MOUTHED" FISHES 



in the low tidal pools, its strong jaws and great teeth the front 

 ones are long and pointed like those of a tiger making it a very 

 dangerous assailant; 



The Gobies have the throat fins joined to form a sucker ; but 

 in the Sucker-fishes (Lepadogaster) this sucker-fin is more perfectly 

 developed. Several of these little fishes may be found near the 

 shore, clinging, when at rest, to stones and rocks with their curious 

 suckers. The spindle-shaped eggs of the Rock Goby are often to 

 be found fixed to the under-side of stones. They are at first colour- 

 less, but as the embryos develop they change to bright green owing 

 to the large green eyes of the little creatures shining through 

 the transparent envelope. If some of the eggs are collected the 

 development of the tiny fishes may be watched, with the aid of 

 a pocket lens, until the membrane of the eggs breaks and the little 

 prisoners wriggle their way out into the water. 



A curious fish allied to the gobies is the Walking- or Jumping- 

 fish (Periophthalmus), that lives on the mud-flats at the mouths 

 of rivers in tropical Asia, Africa, and North- West Australia; It has 

 a long body, a massive head with protruding jaws, and large promin- 

 ent eyes set closely together, while the pectoral fins are remarkably 

 developed and used for locomotion on land. Day writes concern- 

 ing the habits of these strange creatures : " These fishes, from the 

 muscular development at the base of their pectoral fins, are able 

 to use them for progression on mud or for climbing. It is a most 

 curious sight to see P. schlosseri along the side of Burmese rivers ; 

 at a distance the fishes appear like large tadpoles, stationary, con- 

 templating all passing objects, or else snapping at flies or other 

 insects ; suddenly, startled by something, away they go with a 

 hop, skip and a jump, either inland among the trees, or on to the 

 water like a flat stone or piece of slate sent skimming by a school- 

 boy. They climb on to trees and large pieces of grass, leaves, 

 and sticks, holding on by their pectoral fins exactly as if these 

 were arms. Now and then they plant these firmly as organs of 

 support, the same as one places one's elbows on a table ; then they 

 raise their heads and take a deliberate survey of surrounding 

 objects." 



The Jumping-fish is by no means the only fish able to move 

 over the land and live for a time out of the water without 

 inconvenience. Some notable examples among the Teleostei are 



