ON VARIATION. 31 



II. A yellow band posteriorly from orbit, bounded below by a black 

 or brown one 

 a. Saddle spots closed laterally on gastrosteges ; alternate spots 

 entirely on gastrosteges. 



A half collar behind parietal plates, no superciliary 

 stripe ; ' O. d. temporalis, 



aa. Saddle spots closed above gastrosteges ; alternate spots on 

 scales. 



A half collar nearly or quite touching occipital plates, no 

 bands ; alternate spots partly on gastrosteges : 



0. d. collaris. 

 Neck with longitudinal bands ; alternate spots partly on 

 gastrosteges ■. O. d. clerica. 



Neck with bands ; alternate spots entirely on scales : 



O. d. triangula. 



In Fig. 2 are represented vertical, lateral, and in- 

 ferior views of parts of the body of the subspecies tri- 

 angula, taken from a specimen in my collection from 

 Westchester County, New York, which I owe to the 

 kindness of my friend, Mr. T. H. Mead. 



The characters of this form are seen in (i) the 

 presence of a light band extending from the posterior 

 angle of the eye downward and backward, which is 

 bounded by a black border above and below ; (2) a 

 black cross-band on the posterior border of the pre- 

 frontal plates; (3) chevron shaped mark with the apex 

 on the posterior part of the frontal plate, whose limbs 

 extend posteriorly as a band on each side of the neck, 

 where they are fused together, and continue as a sin- 

 gle, broad band for a short distance ; (4) a series of 

 lateral spots which do not extend beyond the scales on 

 to the gastrosteges, and which alternate with the dor- 

 sal spots ; (5) a series of spots on the ends of the gas- 

 trosteges which alternate with the last mentioned; 

 (6) a series of spots on the centers of the gastrosteges 

 which alternate with the spots mentioned under (5). 



