1S91.] ^'^'^ fCope. 



No rudimental lung. 

 C'lotho arietans L. 



Viperidce. 



Crotalidce. 



I. No rudimental lung. 



Bothrops lanceolatus L.; Ancistrodon ptsci«or!/,8 Lacep. ; Crotalopliorus 

 catenatus Raf. ; Crotalus adamanteus Beauv. ; C. confluentus Say. 



II. Willi a rudimental right lung. 



Bothrops pietus Tsch. ; B. erythrurus Cant. ; Teleuraspis scMegelii 

 Berth.; Ancistrodon contortrix L. ; Crotalus horridus L. 



THE SYSTEMATIC VALUE OF THE PULMONARY 

 CHARACTERS. 



I have no doubt of the propriety of the separation of the Uugualiidai 

 from the other Peropoda, on account of its pulmonary characters. Nor is 

 there any doubt in my mind of the necessity of the separation of the 

 Leptognathlna^ from the Xenodontiute, for similar reasons. The genus 

 Heterodon differs very much from the Xenodoutinoe, in tlie possession of 

 an enormous diverticulum of the lung, but as it is not present in the allied 

 genus Lystrophis Cope, its wider distinction may be a questionable pro- 

 ceeding. The very marked characters of the genus Chersydrus charac- 

 terize the family, as well as the osteological characters. It remains to be 

 seen whether the family I termed the Nothopsida3, but which Boulenger 

 unites with the Chersydridie, agrees with it in pulmonary characters. 

 The remarkable tracheal lung or gland distinguishes the Epauodonta from 

 the Catodonta, emphasizing ihat observed in the osteology of the skull. 

 The peculiar form and relations of ihe m ixillary bone in this group resem- 

 ble those of the Soleuoglypha, and there may be some possible connection 

 between the groups. The tracheal body may be a degenerate tracheal 

 lung, such as that division possesses. 



The value of the rudimental right lung as a character of the Colu- 

 broidea is increased by my investigations. In only two genera have I 

 found it present or absent, viz., Halsophis and Pityophis. I am not sure 

 but that I may yet find it in the P. melanoleucus, where I have tailed hith- 

 erto, but I am sure that it is present in some species of Hals.iphis and 

 wanting in others. A natural group of American Colubriuaj, appears to 

 be characterized by its absence, viz., Rhinochilus, Cemophora and Ophi- 

 bolus ; all genera with an entire anal shield. The development of carti- 

 lages in the bronchial foramen or tube of the rudimental lung is not a 

 constant character. I found it in one Heterodon platyrhinus and not in 

 another ; it is present in Vonophis pulcher, but absent in O. sumichrasiii. 



The rudimental lung is often concealed from view and difficult to dis- 

 cover. The best test ot its presence is the foramen which connects it with 



PROC. AMER. PHILOS. SOC. XXXIII. 145. 3 C. PRINTED JUNE 18, 1894. 



