188 BULLETIN 187, UNITED STATES NATIONAL MUSEUM 



ground, and with light borders of the diamonds often absent 



laterally tortugensis 



Upper preocular usually in contact with postnasal, or such contact pre- 

 vented by an upper loreal ; head proportionally larger ; pattern of 

 brown diamonds consisting of aggregations of dark punctations on a 

 cream, buflf, gray, grayish brown, or (rarely) pinkish gray back- 

 ground atrox 



24. Intergenials usually absent; prenasals generally in contact with first 



supralabials ; dark tail rings complete, or broken only on middorsal 



line; adults exceed 900 mm. in length 25 



A pair of intergenials usvially present ; generally no contact between pre- 

 nasal and first supyalabial ; dark tail rings often broken laterally ; size 

 smaller, adults rarely exceeding 900 mm. in length; a pattern of red, 

 circular, ill-defined blotches on a pink or pale red ground color exsul 



25. General coloration pink, red, brick red, or reddish brown ; usually no light 



areas within diamonds; light preocular stripe one or two scales wide 

 (determined at second row of scales above supralabials, if scales are 

 regular), dull and often obscure; supraocular light crossbars usually 

 absent; a pattern of reddish brown, almost unicolor, diamonds on a 



pinkish brown ground color ruber 



General coloration brown, olive-brown, or yellowish brown ; light areas 

 usually present within the diamonds ; light preocular stripe three or 

 more scales wide, bright and conspicuous ; supraocular light cross- 

 bars usually in evidence; a pattern of brown or olive-brown blotches 

 on a buff background lucasensis 



26. More than two internasals (i. e., scales between nasals, and in contact 



with rostral, regardless of size or position) 27 



Two internasals . 28 



27. Light preocular stripe one scale wide below orbit ; light postocular stripe 



one or one and one-half scales wide, usually clearly outlined ; body 

 blotches commonly subrectangular, with even edges and usually with 



a narrow light border viridis viridis 



Light preocular stripe, if present, two or more scales wide below orbit ; 

 light postocular stripe two or more scales wide, often indistinct or 

 absent; body blotches, if in evidence, commonly diamonds, ellipses, 

 or if rectangles, with edges rough or serrated, and often witliout nar- 

 row light borders viridis oreganus 



28. No distinct and evenly outlined supraocular cross bars curving forward 



inwardly ; frontal area not conspicuously depressed 29 



Distinct and evenly outlined light supraocular cross bars curving forward 

 inwardly; outer edges of supraoculars raised above crown, forming a 

 depression in frontal area (particularly evident in life) ; dorsal scales 

 sharply keeled and tuberculate; spinal ridge evident; a pattern of 

 dark brown blotches on a fawn background, usually with black in 

 the lateral corners of the blotches at midbody; tail rings indistinct 

 and incomplete enyo 



29. Head and rattle of moderate size; length of head contained in total 



length (adults) less than 25 times; width of proximal rattle con- 

 tained in length of head more than two and one-half times 30 



Head conspicuously small for a rattlesnake, and rattle relatively large ; 

 length of head contained in total length (adults) 25 times or more; 

 width of proximal rattle contained in length of head less than two and 

 one-half times ; pattern of rather indistinct cross bands or narrow 



