522 MB. F. E. BEDDARD ON THE VASCULAR AND [May 1, 



front of it — the thoracic lung is marked off from the tracheal by 

 a short forwardly extending pouch of the former which lies 

 dorsally, and therefore, as seen in dissection, beneath the lower 

 end of the tracheal lung. Such a forward process of the thoracic 

 lung is common in Snakes, but I have not found it in Coluher 

 longissimius. It has in G. leopardinus obviously nothing to do 

 with the tracheal lung. 



There is a second honeycombed and vascular rudimentary lung. 



In Cohtber inelanoleucus * there is a type of lung differing in 

 many respects from that of the three species of Coluber already, 

 or to be, dealt with. The trachea is continued down the lung for a 

 very great distance. It is from high up in the neck an open gutter 

 and runs as such to a point about half way down, or not far from 

 the posterior end of, the liver. The trachea does not cease at the 

 end of the vascular region of the lung, but extends some way 

 beyond the point at which the lung ceases to be vascular. When 

 a transverse section is made of the lung behind the heart, the 

 appearances presented suggest at first that the trachea is quite 

 independent of the lung. The elasticity of the cartilaginous rings 

 keeps the trachea closed, and produces the impi-ession of a, closed 

 tube running within the lung. It is not, however, closed but 

 freely communicates along its whole length with the cavity of 

 the lung. The lung-tissue does not extend foi-wards beyond 

 the region of the heart ; this species has therefore no tracheal 

 lung. The honeycombed structure ceases in a very abrupt 

 fashion along a line which is rather oblique. I found a pocket 

 running forwards such as is met with in Coluber longissimus 

 and is not uncommon among Snakes. There is a considerable 

 distance in the neck-region between the separated extremities of 

 the ti'acheal semirings. But the membrane which divides them is 

 not swollen out into such a thin-walled sac as occurs in Coluber 

 corals. It is rather thick, and nowhere could I find any traces of 

 a honeycombed structure, which, considering the abrupt way in 

 which the lung ends at the heart, would hardly be expected. 

 Furthermore, there does not seem to be in this serpent any 

 rudimentai-y left lung at all. If it be present, which I doubt, it is so 

 small as to have escaped my observation. 



It is clear that Coluber inelanoleucus presents more differences 

 from the three species of Coluber that have been described than 

 any of them do from each other. The absence of a rudiment of 

 the left lungt, the enormous extension down the lung of the 

 trachea, and finally the abrupt ending of the lung-tissue in the 

 region of the heart, are the salient points of difference. I am much 

 inclined to doubt whether the inclusion of this species in the same 

 genus with the three species already referred to is, anatomically 

 considered, a sound procedure. But I hope later to offer some 

 observations upon the systematic arrangement of certain Ophidia. 



* I dissected two examples. 



t Even if this has been overlooked considerable differences remain. Cope, 

 howevei", was unable to find it like myself. 



