1909.] OF SNAKES OP THE GENUS BOA. 921 



of any such seam ; the bronchus in this lung ends abruptly, and 

 there is no diminution towards or at the end in the calibre of its 

 semirings. On the other hand, in the larger lung the cartilages, 

 though continuing to the end of the intrapulmonary bronchus, 

 get successively nai-rower and narrower. I have not observed in 

 other Boas and Pythons where a fibrous continuation of the 

 intrapulmonary bronchus occurs, any suggestion of a branching of 

 this seam, which I now proceed to describe in Boa occidentcdis . 



Text-fio-. 283. 



A 



A magnified repveseutatiou of the end of the bronchial gutter in the same lung- as 

 shown in text-figs. 281 & 282, to show the double origin of the seam and its 

 independence from the walls of the pulmonary alveoli. 



At a considerable distance behind the termination of the intra- 

 pulmonary bronchus the seam gives off a branch (see text-fig. 282, 

 p. 919) which runs obliquely towards that wall of the lung which 

 is contiguous with the wall of the smaller lung. This seam is no 

 smaller than the main seam, of which it is a bi^anch, and shows 

 the same characters that have been enumerated above. It ends 

 by bifurcating into two branches. 



This fact appears to me to be of the most interesting 



