696 REPORT OF NATIONAL MUSEUM, 1898. 



the proximal part of the dorsal lung. It is sometimes connected to the dorsal lung 

 by a short tiibe, in which cartilaginons half rings are seen in bnt two of the genera 

 examined, \iz, Hetcrodon and ConojMs. The lumen of the rudimeiital lung maybe 

 lined by the same reticulate structure as is seen in the dorsal lung, or its walls may 

 be smooth. In some Colubroidea the rudimental lung is absent, but such species are 

 relatively few. 



The dorsal lung may present proximally alongside of the trachea an auricle or 

 pocket, and this is so developed in the genus Heterodon as to reach to the head 

 without communication wilh the trachea other than that furnished by the normal 

 portion of the lung. In the Soleuoglypha, without exception, this extension of the 

 dorsal lung is present, aud extends to the head, and its lumen is continuous with the 

 trachea throughout its length. The same structure exists in the genera Hydrus and 

 Hydrophis, and also in the peropodous genus Ungalia, which differs besides from 

 other Peropoda in having but one post- tracheal lung. Finally, the tracheal lung, as 

 I have called it, is distinct from the true lung in Platurus and in Chersydrns. In 

 the former of these genera the trachea is not separate from the lumen, while in 

 Chersydrns 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. 

 There is no lumen in the tracheal lung in Chersydrns. In Typhlops we have a still 

 further modification of the tracheal lung. It is without lumen, and is composed of 

 coarse cells of different sizes. These have no communication with the trachea or 

 lung that I can discover, nor any efferent orifice. It has occurred to me that this 

 structure, which extends from the heart to the throat, may not be a pulmonary 

 organ. 



I have referi'cd to the dorsal and ventral positions of the two lungs. The rudi- 

 mental lung is to the right of the dorsal lung in the Colubroidea, but in the Uysiidai 

 it is to the left. It is quite questionable which lung this rudiment in this family 

 really represents. In the Typhlopidte the single lung is on the right side and extends 

 from the heart to the liver. It has the position of the rudimental lung of the Colu- 

 broidea, aud may represent it, I can not decide this question without further mate- 

 rial. In Glaucoma there is but one true lung, and this is ventral in position, and 

 originates to the right of the heart, so that in this genus also it may represent the 

 rudimental lung of the Colubroidea. There is here no tracheal Inng or organ.' 



I now give a synopsis of the characters observed in the sj^ecies examined. 



CATODONTA. 



Glaucoma dulcis Baird and Girard. A single elongate right lung; no rudiment of 

 left lung. No tracheal lung. 



EPANODONTA. 



Typhlops liberiensis Hallowell; T. reUculatns Linnaeus. A right lung which is not 

 elongate; no rudimental left lung. A cellular body surrounding the trachea, aud 

 extending from the heart to the throat, without lumen or connection with the trachea 

 or lung. 



Tlie presence of the tracheal lung ( ?) and the freedom of the maxillary bone are 

 points of resemblance to the Soleuoglypha ! 



TORTRICINA. 



Ilysiidce. 



Two lungs, the ventral one to the left side of the middle line, rudimental, but 

 lined with pulmonary tissue like the other lung, and less reduced than in the Colu- 

 broidea. 



Cylindrophis maculata Linnseus, The right lung extends only to the liver. 



Ilysia scytale LinniEUS. The right lung is larger. 



I See Peters, Raise nach Mozambique, III, p. 100, pi. xiv A, 1882. 



