OTHER DIPNOI 



gills of the fish, which are adequate enough in favourable 

 conditions. It is in fact exactly in the condition of a 

 rather elderly tadpole. The very young tadpole has 

 merely gills like a fish ; later on, the lungs appear, 

 while the gills persist ; later still, the gills vanish and 

 the lungs alone remain : it is, however, now a frog. 

 Ceratodus remains for its whole life in the tadpole con- 

 dition. It would not be a gross exaggeration to describe 

 it as a huge scaly tadpole. 



The Australian mud fish is one of those " friendless " 

 creatures, a survival from past times, when creatures 

 were apt to be a little less decided as to their relation- 

 ships than at present. It is a link between fishes and 

 amphibians. Ceratodus itself has not a tadpole ; but 

 its near allies, the African mud fish, Protopterus, and 

 the South American Lepidosiren, have newly-hatched 

 larvae which are immensely like young tadpoles. Every- 

 body must have noticed the way in which the tadpoles 

 of our common frog hang on to the leaves of aquatic 

 plants by their chin, which they press firmly thereto 

 as the Red Queen pressed her chin upon the shoulder 

 of Alice. A sucker achieves this anchorage, and the 

 same sucker is present in the young mud fishes of 

 America and Africa. The Paraguayan mud fish, once 

 so scarce that it was represented in European museums 

 by about three specimens, has long furnished a succu- 

 lent meal in certain regions of South America. It has 

 been brought home in abundance and carefully studied 

 by Professor Graham Kerr ; it is therefore not by any 

 means unlikely that the visitor to the Zoo will have the 

 opportunity of seeing side by side this creature and its 

 Australian relative. In any case he will be practically 

 certain to have the chance of seeing Protopterus of 

 Africa. 



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