286 PROCEEDINGS OF THE ACADEMY OF [Apr., 



Specimen. — Brit. Mus. Ex. No. 19a. South America. Female: 

 total length 480, tail 20 mm. 



Squamation. — The number of §cale rows, the sequence in which 

 they are added, suppressed, and the gastrostege level at which these 

 changes occur, are as follows: 



19 rows, VI row added, right 55th, left 53d gastrostege, making: 

 21 rows, V row ends, right 206th, left 202d gastrostege, leaving: 

 19 rows, VI row ends, right 220th, left 221st gastrostege, leaving: 

 17 rows, which are continued to the vent. 



Gastrosteges 236; anal divided; urosteges 12 and a terminal 

 scute, the first and second paired, the remainder entire. Frontal 

 barely touching the occipital; supraocular larger than the parietal; 

 supralabials 5, the third and fourth touching the ocular shield; 

 infralabials 5, the first pair the deepest and in contact behind the 

 long mental; a single pair of large geneials which are not in contact; 

 three azygos gular shields. 



Ajiatomy. — The tracheal cartilages terminate at the level of the 

 61st gastrostege. The tracheal memhrane is narrow and is not lined 

 with pulmonary tissue. The right lung extends from the 57th to 

 the 135th gastrostege; it is 152 mm. long, and lined throughout with 

 pulmonary tissue. There is a small free apex, 2.5 mm. long, that 

 extends to the 57th gastrostege; it is in relation with the right side 

 of the trachea, and the lumen is continuous with that of the lung. 

 The lung terminates in a blunt end which is 3.3 mm. in diameter. 

 The left lung, 5.5 mm. long, extends from the 58th to the 61st gastro- 

 stege. It is in relation above with the end of the trachea and the 

 right lung, to the right with the apex of the heart and the inferior 

 vena cava, below with the ventral wall of the pleural cavity, and to 

 the left with the stomach. It is lined with pulmonary tissue through- 

 out. The left bronchus opens from the ventral side of the trachea 

 opposite the 60th gastrostege. It enters the lung at the junction 

 of the middle and the posterior one-third. The liver in this species 

 and in Cylindrophis rufus is peculiar in that macroscopically it 

 appears finely reticulate, with lines composed of minute black dots. 



The anterior portion of the liver from the tip to the level of the 

 126th gastrostege is composed of the left lobe, along the right side 

 of which courses the large inferior vena cava: At the 126th gastro- 

 stege this vessel begins to furrow the ventral and left side of the 

 liver and divides the organ into right and left lobes. These lobes 

 continue posteriorly; the right, which is 6 mm. the longer, ter- 

 minating at the 147th, and the left at the 144th gastrostege. 



