1903.] AXATOMY OF THE HAMADRYAD SNAKE. 327 



anterior bit of the lung which in Ophiophagus lies above the 

 entrance of the bronchus, or it may be an increase aiid conversion 

 into lung-tissue of the merlian membranous region of the trachea. 

 Quite recently the late Prof. E. D. Cope has investigated — but 

 apparently only in a preliminary way — the lungs of various 

 snakes, some of which were known and others unknown to 

 previous observers. In the long list of Ophidia investigated by 

 Cope representatives of most groups occur, but he had not the 

 opportunity of examining the Hamadryad. The pith of his 

 paper*, so far as concerns the subject in hand, is contained in 

 the following sentences: — "In the Solenoglypha, without excep- 

 tion, this extension of the dorsal t lung is present, and extends to 

 the head, and its lumen is continuous with the trachea through- 

 out its whole length. The same structure exists in the genera 

 Hijdrus and Hydrophis ; and also in the Peropodous genus 

 Ungcdia, which diifers besides from other Peropoda in having 

 but one posttracheal lung. Finally the tracheal lung, as I shall 

 call it, is distinct from the true lung in Platyurus and in Cher- 

 sydrus. In the former of these genera the trachea is not separate 

 from the lumen ; while in Chersydrus it is distinct. It, however, 

 communicates with the cells of which the lung consists in this 

 genus by a series of regularly placed foramina on each side." 



It is a little difficult to draw conclusions from so abbreviated a 

 statement of fact ; but I am inclined to suppose that Chersydrus 

 (also a Colubrine, though aglyphous) comes nearest to Ophio- 

 phagus though obviously difieiing much in detail. I take it that 

 the conditions which characterise Ophiophagus are an extreme 

 modification of those apparently found in Chersydrus : that the 

 metamerically arranged pouches in the former, with their seines 

 of single orifices into the trachea, are the remains of what Cope 

 terms the " tracheal lung," in which the respiratory function has 

 been replaced by some other use. In the absence, however, of 

 complete details as to Chersydrus and the other genera to which 

 Cope refers, it is rash to form a definite opinion. It must be 

 borne in mind that there is in Ophiophagus no connection with 

 the lung. The only structure among Sauropsida, other than 

 serpents, which I can think of as obviously comparable to this 

 series of pouches in Ophiophagus^ is the tracheal pouch of the 

 Emu J. That bird in a quite similar fashion shows a slit on the 

 trachea where the rings fail to meet in the middle line. It is, 

 however, ventral rather than dorsal in position, and there is but 

 a single slit. It leads into a thin- walled outgrowth of the lining 



* " On the Lungs of the Ophidia," Proc. Amer. Phil. Soc. xxxiii. 189 i, p. 217. The 

 facts are also to be found in two other memoirs, viz. " The Classitication of Snakes," 

 Amer. Nat. xxviii. 1894, p. 831, and " The Classification of the Ophidia," Trans. 

 Amer. Phil. Soc. xviii. p. 188. 



f " Dorsal " as used by Cope is the equivalent of " right " in Mr. G. Butler's 

 paper " On the complete or partial Suppression of the Right Lung in the Amphis- 

 bajnidaj and of the Left Lung in Snakes and Snake-like Lizards and Amphibians," 

 P. Z. S. 1895, p. 691. 



X Cf. Murie, "On the Tracheal Pouch of the Emu (Dromcens nnvce-lioUandice)." 

 P. Z. S. 1867, p. iO-5, where previous literature is cited. 



