106 NATUEE STUDIES. 



tlieir existence. But all analogy leads us to expect 

 that such " links " once existed ; and I wish now to 

 describe certain interesting examples of such inter- 

 mediate forms , as they are called, culled from varied 

 groups of the animal world. In a word, if I am able 

 to show that we possess at present in the world around 

 us certain animals which undoubtedly connect distinct 

 groups, I may claim the strong support of such 

 examples in favour of the idea that " links " that are 

 now ' c missing " where we desire their presence, once 

 did exist. 



Fig. 1. Lepidosireii anncctens, or Mud-fish, showing the limb- 

 like fins. 



One of the most curious groups of fishes is that named 

 by geologists the Dipnoi. This name means " double- 

 breathers,^ and the significance of the name will be- 

 come apparent later on. Of this order of fishes there 

 are two chief examples. The Lepidosirens (Fig. 1), or 

 " mud-fishes," found in the rivers Amazon and Gambia, 

 form the first of these examples ; whilst a curious fish, 

 occurring in Australian waters, and known as the 

 Ceratodus, or ' ' Barramunda," represents the second 

 type. This latter fish is the " Jeevine " or " Teebine " 

 of the Australian natives. Now, in looking at either 



