PULMONARY EVOLUTION IN MAMMALIA 109 
Left lung: D! arises from the dorso-lateral circumference of 
the stembronchus at the level of the caudal border of V', the 
pulmonary artery descending between them. D2—-D#4 are some- 
Fig. 2. Dorsal view of model shown in figure 1. Ep., eparterial bronchus; 
A., ascending branch of first left ventral hyparterial bronchus; V!-V4, ventral 
hyparterial bronchi; Cd., right cardiac bronchus; D!-D4, dorsal bronchi. 
what smaller than the same derivatives of the right stembron- 
chus, but otherwise correspond to them in level and proliferation. 
The pulmonary reconstruction of the 8 mm. embryo of 
Dasyurus viverrinus, which is slightly less advanced than the 
