Cope.l ^""^ lApril 17, 



sus, but is present or absent indifferently in several others. The number of 

 supraoculars in the principal row may be four or five in most of the species. 

 The greatest diflBcuIty is experienced in distinguishing the North Ameri- 

 can species. They are much fewer in number than has been represented 

 to be the case, and the few that are admissible do not present the strong 

 characteristics that most of those of more southern regions. The S. undu- 

 latus has an almost continental distribution in North America, within the 

 range of temperate and subtropical climates. 



In the following synopsis little attention is devoted to coloration, for 

 although it furnishes important characters in many of the species, in 

 others it is less distinctive. This part of the description is left for a fuller 

 monograph. 



I acknowledge here the aid I have derived from M. Bocourt's work 

 already cited. This naturalist in identifying and figuring the types of 

 Wiegmann, has rendered an important service to herpetology. 



I. Femoral pores 3-6. 

 Facial scales smooth ; supraoculars wide ; one parietal plate ; two can- 



thals ; no collar S. horridus. 



Facial scales keeled ; laterals smaller than dorsals, directed upwards and 



backwards ; two canthals ; two parietals ; colors bright. . . S. siniferus. 

 Facial scales keeled ; laterals smaller, directed upwards and backwards ; 



two parietals ; one canthal ; colors dull S. squamosus. 



II. Femoral pores ten and more. 



A Scales of the sides granular. 

 Facial scales keeled ; supraoculars wide ; both frontals divided ; parietals 



two ; canthals two ; ten scales in head length S. utiformis. 



A A. Scales of sides squamous. 



* Facial scales keeled or wrinkled. 



f One scale on canthus rostralis. 

 One parietal ; twelve dorsal scales in a head length S. chrysostictus. 



ft Two scales on canthus rostralis. 

 Lateral scales equal dorsal, longitudinal ; anterior frontal single ; supra- 

 oculars long ; two parietals S. scalaris. 



Like ceneus, but head and limbs shorter ; supraoculars short ; 8 scales in 



a head length, color green S. oeneus. 



Lateral scales smaller than dorsals, directed obliquely; supraoculars short, 



anterior frontal divided ; two parietals >S. variabilis. 



** Facial scales smooth. 



t No color band across nape. 



X One scale on canthus rostralis. 

 Dorsal scales converging to the middle line ; two small parietals ; two 



rows blue spots on the belly /S'. jiyrrhocephalus. 



Dorsal scales in parallel rows ; one large parietal ; belly unspotted 



S. malachiticus. 



XX Two scales on the canthus rostralis. 



H Scales small ; 12-23 in a head length. 



§One row of large supraoculars, with granulars. 



