CROCODILTANS, LIZARDS, AND SNAKES. 335 



aa. I'^einoral pores exceeding 10. 



One scale on cantbiis rostralis; 1 parietal; 12 dor- 

 sal scales in a liead length ; dorsal stripes and 



lateral spots yellow S. chrysostictiis Cope. 



Two cantbal scales; lateral scales small ; 2 parie- 

 tals; dorsal stripes yellow, side patches pink- 

 purple S. variahilis Wiegmann. 



BB. Head plates smooth, or if rarely wrinkled, the frontal plate not divided. 

 a. Scales small; 12-22 in a head length. 



/i. One row of large supraoculars, with laterals. 



Two or three parietals; frontal divided; nineteen 

 scales in a head length ; lateral scales much 

 smaller than ventrals; 17-20 femoral pores; a 

 black shoulder patch ; a pale dorsolateral band. 



iS'. couchii Baird. 



Two parietals; lateral scales equal ventrals; 



twelve dorsals in a head length ; forty-five from 



occiput to groin, mucronate ; dark green above. 



S. vandenbiirgianus Cope. 



Three parietals; 14-15 scales in a head length; 



color in longitudinal bands; frontal undivided. 



S. graciosuti Baird and Girard. 



fifi. Two or more rows of flat supraoculars. 



Three or two parietals; 12-15 scales in a head 



length ; no bands *S'. (irammicus Wiegmann. 



Three parietals; 18-22 scales in a head length; 

 color in narrow cross lines. 



S. microlepidoius Wiegmann. 

 Two parietals ; fifty non-mucronate scales between 

 occiput and groin ; a black light-bordered col- 

 lar S. ornatus Baird. 



a(x. Scales larger; ten and fewer in a head length. 



£E. Thirty to forty rows of scales between occiput and groin. 

 C. Dorsal scales not mucronate. 



Two cantbal scales; two rows of larger supraor- 

 bitals; frontal undivided; two parietals; a com- 

 plete black pale-bordered coVsir.S.jarrovii Cope. 

 CC. Dorsal scales mu(;ronate. 



r/. One cantbal scale; one row of large supraoculars. 

 G. No black neck collar. 



One large parietal ; large su])raoculars undivided ; 

 males blue green with blacik throat. 



jS'. vuilachitivNS f'ope. 

 7/;/. A ])lack neck collar. , 



"Collar incomplete above; head less than one-fifth 

 of length of head and body; throat blue;" 



Bocoiirt S. luna^i Bocourt. 



Collar very narrow, not pale bordered, a little 

 interrupted above; head less than one-fourth of 

 head and body; throat dark slate, yellow spot- 

 ted S. ferrariperezi Cope. 



('ollar complete, yellow bordered before and 

 behind ; head about one-fifth bead and body ; 

 throat, belly, and groin black. 



<S'. melauoyaster Cope. 



