1108 



REPORT OF NATIONAL MUSEUM, 1898. 



as liigb as wide. Three preorbitals; tlie upper more tbau three times 

 as large as either of the two lower, its inner angle produced to the 

 vertical, separating the superciliary and postfrontal. Two postorbitals ; 

 upper largest. Eight upper labials ; sixth and seventh four times as 

 large as either of the three anterior ones. Ten lower labials; fifth 

 and sixth largest. Dorsal scales in twenty-one to twenty-three rows, 

 narrow, acute posteriorly ; first lateral row much the widest. 



Body above, with broad, lustrous, brownish-black half rings on a 

 light-yellowish ground. The black rings six to eight scales wide in the 

 middle, narrowing very much, or even rounded off, laterally, sometimes 

 not extending quite to the abdomen. Light intervals, one or two scales 



Fig. 316. 



SiBON SEPTENTRIONALE KENNICOTT. 

 = 1. 



Matamoras, Tamaulipas, Mexico. 



Cat. No. 4267, U.S.N. M. 



wide, on the vertebral region, widening to three or four times as much 

 nearer the abdomen. Abdomen and lower surface of head uniform 

 light yellowish. An irregular light occipital ring. Upper labials and 

 anterior part of head brownish, lighter than the dark dorsal band. 



The largest species of the genus, ranging from Panama to Cameron 

 County, Texas, inclusive. 



Sihon septentrionaJe Kennicott. 



