528 MR. F. E. BEDDARD ON THE VASCULAR AND [May 1, 



relations of the tracheal to the thoracic lung, bears the same 

 relation to Tarhopliis as does Coluber cordis to e. g. Coluber 

 melanoleucus. Finally, I have to point out that the bronchus does 

 not extend very far down the functional lung. The bronchial 

 gutter, which is quite flattened out and not gutter-like as it is 

 in Coluber *, reaches back to a point not more than half an inch 

 behind the apex of the heart. 



In a fresh example of Boodon lineatus the conditions of the 

 lung were very plainly visible on opening the body. The limits 

 between the vascular and the anangious regions of the respiratory 

 organ were easily mapped. The trachea was seen to be provided 

 dorsally with a tracheal lung, the cells of which were especially 

 plain and presented the appearance, before the trachea was split 

 up, of bubbles of air lying between the ends of the tracheal rings. 

 At a level with the commencement of the ventricle, this tracheal 

 ring took on a red hue, this part being vascular. The vascularity 

 of the lung was seen to continue down about an inch along the 

 liver, before the middle of which it ceased to be visible. The 

 bronchus is not, in this species, continued far down the lung. It 

 ceases, in fact, at the very commencement of the thoracic lung, A 

 careful examination failed to reveal any trace of a second rudi- 

 mentary lung. There was no perforation of the open bronchus 

 at the end of the heart. Neither is there any forward extension 

 of the functional lung headwards. The lung of this Snake is 

 therefore primitive in that it has retained considerable traces of 

 the tracheal lung, but modified in the entire absence of a second 

 lung and of a forward extension of the lung headwards. A second 

 specimen showed identical characters. 



/Se2)edon hcemachates. — In view of its relationship to the Hama- 

 dryad, I have been particularly anxious to examine this Snake, 

 which, however, shows only slight resemblances to the peculiar 

 precardiac diverticula of the windpipe in Opliiophagus'f. The 

 single lung — I have been unable to find a rudimentary lung + — 

 commences to be vascular in the region of bhe heart and con- 

 tinues to be so a little distance down the liver. The lung-tissue 

 does not, however, abruptly end or begin anteriorly ; it commences 

 gradually at about on a level with the auricles of the heart, this 

 portion being the equivalent of the tracheal lung of other species, 

 though not vascular. In front of this again the ends of the 

 tracheal rings are separated by a very wide membranous interval, 

 fully as wide as the true thoracic lung, and forming an air-sac 

 continuous with the lung which extends up to the head. The 

 arrangement is, in fact, like that of Coluber cordis described above. 

 The tracheal gutter does not extend far into the thoi'acic lung and 

 is continued a little way further by a fibrous band. 



The new facts which have been here detailed seem to afibrd 



* See p. 522. 



t P. Z. S. 1903, vol. ii. p. 332. 



X Milne-Edwards (Phys. et Anat. Cornp. ii. 1857, p. 308 footnote) states th.it there 

 is one. 



