326 MB. F. E. BEDDARB ON THE [NoV. 17, 



of the compartments (about 22), which fact, coupled with the 

 smaller dimensions of the snake, bears ovit, to a certain extent, 

 my belief that the smaller intercalary sacs grow with the increase 

 in size of the snake. 



Text-fig. 40. 



.-.^C^V^^ 



Ending of trachea in lung of OpMopliagus. A, foramina leading into air-sacs ; 

 B, terminal air-sac ; C, entrance to rudimentary lung ; D, lung. 



The accompanying sketch (text-fig. 40) shows the relation of 

 the last of these air-sacs to the lung. It will be observed that in 

 Ophiojihagus as in Naia there is a rudimentary lung as well as 

 the fvdly developed one, and that the bronchus enters the fully 

 developed lung about half an inch posteriorly to the commence- 

 ment of the latter. The rings of the bronchus do not extend 

 down the lung beyond the origin of the bronchus to the rudi- 

 mentary lung, but a narrow white seam is to be observed which 

 is developed for some distance along the lung. The median thin 

 fibrous wall of the trachea, of covirse, is in contact with the lung- 

 tissue ; but there is no transitional area between the two. The 

 dark red vascular lung begins abruptly. The last orifice from 

 the trachea is shown in the figure, and beyond it will be seen a 

 flap with a crescentic edge which covers over a short sac which 

 is the last of the series of neck-sacs and in which the trachea 

 may be said to terminate. The wall of this terminal sac is 

 shown in the drawing to be perfoi'ated by a foramen, which, I 

 admit, may be artifact. I am unable to be positive about the 

 matter. If it is not, then it must be a branch of the terminal 

 sac. It must be further observed that the lung can be seen 

 through the terminal sac which thus lies ventrally of that organ. 

 I have satisfied myself that there is no communication between 

 the terminal air-sac and the lung, except, of course, indirectly 

 through the trachea. 



So far as I can ascertain, there is nothing precisely similar to 

 this known in other Snakes. Many anatomists, however, have 

 described a continuation of the lung- tissue it,p the trachea, i. e. 

 towards the head*. This may be merely an extension of the 



* For instance, Meckel, Anat. Comp. (French translation), Paris, vol. ii. 1838 ; 

 Schlegel, ' Essai sur la Physionomie des Serpents,' Amsterdam, 1837 ; Siebold & 

 Stannius, Handbuchder Zootomie, 2"Buch, Berlin, 1856 (2nd ed.) ; Milne-Edwards, 

 ' Le9ons sur Iji Physiologic et 1' Anatomic comparee,' t. ii., Paris, 1857. 



