ioo A BOOK OF WHALES 



else of first-rate importance to make the comparison 

 stronger. As undoubted whales occur back to the 

 Eocene they have possibly come off from some earlier 

 stock still, and Professor Albrecht has advanced and 

 ingeniously supported the view that the Cetacea are 

 the nearest thing now existing to the necessary, but 

 unfortunately hypothetical, " Promammalia," the race 

 which orave rise to all mammals. His arguments will 



o o 



be partly gone into here ; for at any rate they give 

 some colour to a primitive ancestry of our whales, 

 a result to which other considerations chiefly the 

 failure to tack them on even with probability any- 

 where else seem to drive us. 



Unfortunately, as a general rule, it is by no means 

 easy to distinguish between simplicity which is the 

 effect of degeneration and simplicity which may be 

 fairly interpreted as a retention of earlier and simpler 

 conditions of structure. Sometimes it seems to be 

 obvious enough to which category to refer an appar- 

 ently primitive state of affairs in an organ. For 

 example, while everyone admits nowadays that the 

 Amphibia are close to the fishes, no one would prob- 

 ably suggest that the total absence of lungs in 

 certain Salamanders is due to the final disappearance 

 of the air bladder of the fish-like ancestor, whose 

 disappearance is commencing to be indicated by the 

 loss of a connection with the oesophagus in many 

 fishes. It is a question of simplification and de- 



oreneration within the tribe of newts themselves. 

 t> 



And when Professor Albrecht* alleges the absence 



* " Uber die Cetoide Natur der Promammalia," Anat. Anzeig.. i., p. 338. 



