EPARTERIAL BRONCHIAL SYSTEM. 133 



these, as on the left side, gives off two terminal tertiary branches^ 

 which are studded with monopodia lateral twigs. 



The two tertiary branches resulting from the division of the 

 medial secondary bronchus (^B"^ are characterized by obtaining 

 their arterial supply through a large trunk passing from the 

 main pulmonary artery ventro-caudad between the cephalic and 

 caudal trunks (angle between A and E), and inclining mesad 

 across the secondary lateral branch of the caudal trunk {B'^ to 

 reach the terminal divisions of the medial branch of the same 

 trunk (^^'). The topography of this arterial vessel (PL XVI, C) 

 is entirely characteristic of the usual blood-supply to the infra- 

 cardiac, or Azygos lobe in other Mammalia (cf. infra). 



II b. Taxidea Americana — American Badger. 



Second specimen, large full-grown male. Corrosion prepara- 

 tion of bronchial system and pulmonary artery. Columbia 

 University Museum, No. 1255. PL XVII. 



Presents the same characters as the first specimen as regards 

 the tracheal bulla, and the derivation of the cephalic and caudal 

 primary trunks (/^ and B). The tertiary branches are more 

 fully developed and give off more numerous and larger mono- 

 podia lateral twigs. 



The main interest, compared with the first specimen, centers 

 around the cephalic trunk (^A) of the left lung. The trunk is 

 only slightly smaller than the one of the right side. It divides 

 into a large cephalic or apical branch {A'^ and a very much 

 smaller lateral branch (A"\ while on the right side the primary 

 cephalic trunk A divides into two nearly equal secondary 

 branches (yA' and A"^. We may, therefore, assume that the 

 large left cephalic bronchus of the younger specimen (PL XVI, A^ 

 corresponds in the main to A' of the older animal, and that one 

 of the proximal lateral branches develops into branch A" of the 

 adult. 



The asymmetry of the right lung compared with the left is 

 well marked. The main secondary branches {A' , A") derived 

 from the right cephalic trunk (A) exhibit a tendency toward 

 complete separation and individual independence. The arterial 



Annals N. Y. Acad. Sci., XI, May 18, 1898 — 10. 



