John Lewis Bremer ' 73 



Following Selenka's suggestion, then, it seems to me that we find 

 in the lung of the opossum an epitome of the evolution from reptilian 

 to mammalian lung, and that the chief points are the loss of the left 

 eparterial bronchus in mammals, and the addition to the reptilian lung, 

 which consists only of bronchi and bronchioles, of a new apparatus, with 

 a different and more complicated system of branching, and with walls 

 better adapted for breathing — the infundibular portion of the lung. 



