FOUND LINKS. m 



these forms the breathing in air is contrived in a 

 different fashion from that process in the mud-fishes, 

 and has no connexion with any " lung." 



Let us now reflect that a frog itself begins life as 

 a fish. The " tadpole " has gills and a fish-heart, 

 whilst it has no lungs. Ultimately it acquires lungs 

 and loses gills and tail as its mature shape is attained. 

 Summing up these plain facts of zoology, I think it 

 is not difficult to see that in the mud-fishes and 

 "Jeevine" we find a "link" between the lower 

 water-living fishes and the air-breathing frogs. If 

 we suppose that a form like the mud-fish could rid 

 itself of its gills when it became adult, and that it 

 could throw off the scales of the fish, and develop 

 the limbs of the frog, we might figure to ourselves 

 the ascent of the frog-type from the fish-type. There 

 is nothing more wonderful or impossible in this idea 

 than in the veritable fact that every frog is at first a 

 fish, then a tailed newt, and only ultimately becomes 

 the amphibian. Anyhow, one fact seems clear 

 enough, that fishes and frogs two utterly distinct 

 classes are ' ' linked " by the mud-fishes and 

 " Jeevine " ; and this single fact in itself supports 

 powerfully, in a rational view of matters, the theory 

 that the air-breathing tribes of animals sprang origin- 

 ally from water-living forms. We shall see in future 

 papers that f ' links " even of stranger kind unite 

 classes of animals as dissimilar as the fishes and the 

 frogs. 



