138 MK. F, E. BEDDARD ON THE ANATOMY [Mar, 3, 



gutter. The exact disposition of the bronchus and its relations 

 with the lung requires further study in these animals. In all 

 Pythons, on the other hand, which have been examined from 

 this point of view, the lungs agree with each other to differ 

 fi'om those of Boa, Eryx, and Corallus madagascariensis in the 

 shortness of the intrapulmonaiy bronchus. This varying dis- 

 position of the bronchus would appear therefore to be of generic 

 value at least in some Boidge ; it becomes therefore a matter of 

 some importance to note that in Corallus cookii the conditions 

 observable in Cor alias madagascariensis are not repeated, but 

 that the intra pidmonary bronchus of the former snake is short. 



Thus the two snakes, although belonging, in the opinion of many, 

 to the same genus, show a point of difference in the structure 

 of the lungs which in other Boidfe is at least of generic value. 

 In Corallus madagascariensis there is not, as it would appear, 

 any trace of the tracheal lung. In Coralltts cookii, on the other 

 hand, the extension forward of the soft tissues of the lung 

 between the separated ends of the semirings of the ti'achea, is, 

 for a short distance, invaded by lung-tissue. The cellular 

 arrangement is quite visible. It is not uncommon among snakes 

 for the semirings of the bronchus to be continued upon the lung 

 as a fibrous seam, which seems to mark a shrinkage of the 

 bronchus itself ; this is the case with the lung of Corallus 

 madagascariensis. It must be borne in mind that this seam is 

 not a structure differing in any essential from the intenial walls 

 of the lung. It is simply produced by a coincidence in direction 

 of the walls of a number of lung-alveoli. That there is this 

 coincidence, and in a longitudinal direction immediately following 

 upon the end of the intra pulmonary bronchus, would seem to 

 indicjite the gradual obliteration of a formerly more extensive 

 intra pulmonary bronchus. The shrinkage of this through nar- 

 rowing and finally obliteration would, in my opinion, leave a 

 straight line with pulmonary alveoli on each side, the alveoli 

 being in consequence symmetrically arranged. This is, at any 

 rate, a. possible explanation of the phenomenon. 



Another view might be held which will be explained directly. 

 While Coralhcs madagascariensis is characterised by the possession 



Explanation of Text- figs. 21 & 22 (opposite). 



Text-fig. 21. — Larger lung of Corallus cookii cut open to display the entrance 

 thereinto of the trachea. 



a. Forward extension of the lung lying dorsally to the trachea, br. Aperture 

 of bronchus of smaller lung. tr.L Tracheal lung. 



Text-fig. 22.- — The larger lung of another example of Corallus cookii, to he 

 compared with that represented in text-fig. 21. 



Forward ca'cal extension of larger lung. I. 2. Smaller lung, below which is seen 

 its forward ctcial extension projecting to right of trachea, s, "beam" lunning 

 along lung. tr.l. Tracheal lung. 



