140 OUR EEPTILES. 



rated the larvae of the dragon-flies (Libellula), 

 which are exceedingly destructive ; the larvae 

 and imago of the great water-beetle (Dytiscus 

 marginalis) ; the boat-flies (Notonectidce) , the 

 various species of newts, and several fish, such 

 as the bearded loach (Gobitus barbatula), and 

 the stickleback (Gasterosteus aculeatus). Finally, 

 he concludes that not one in a thousand of the 

 young frogs which emerge from the egg in spring 

 ever reach their winter quarters. 



Were it not for the unbounded fertility of the 

 frog and toad, they would be totally extermi- 

 nated in one year by the unceasing attacks of 

 their numerous terrestrial and aquatic foes. 

 Should this fertility be checked by any cause 

 whatever, these creatures, like their giant pro- 

 totypes of the Mesozoic and Cainozoic ages, 

 would soon be known only by their remains. 



Its general appearance is similar to that of 

 the last species, but the eyes are more project- 

 ing, with the eyelids very much elevated above 

 the crown ; porous protuberance behind the eyes 

 not so large ; toes on the fore feet more nearly 

 equal ; the third notwithstanding a little longer 

 than the others; first and second not shorter 

 than the fourth ; hind legs not so long as the 

 body; the toes on these feet much less palmated 

 than in the common toad ; the sixth toe scarcely 

 at all developed; skin similarly covered with 



