22 SYNOPSES AND DESCRIPTIONS. 



subtriangular or fused, sometimes displaced by the nasals. Scales keeled, 

 except in Hydrops. 



Scales keeled; 



nasal divided; 



teeth smooth in continuous series; 



loreal present tropidonattjs. 



loreal absent or present storeria. 



nasal grooved or divided ; 



postmaxillary teeth larger and isolated 



HELICOPS. 



scales smooth; 



nasal grooved or divided ; 



postmaxillary teeth little larger hydrops. 



Tropidonotus. 



Kuhl, 1826. 



Stout to slender, tapering to head and tail, belly round; head distinct, 

 crown flat, occipital tract broad, snout narrow; tail tapering to a point. 

 Eye moderately large, pupil round. Teeth smooth and equal, or posterior 

 a little larger. Head-shields normal, anterior small. Nasal in two parts, 

 nostril between. Internasals small, narrowed anteriorly or triangular. 

 A loreal. Preoculars 1 — 3. Postoculars 2 — 5. Suboculars present in 

 T. cyclopium. Scales keeled, pointed, truncate or emarginate, in 17 — 33 

 rows, outer broader. Subcaudals in two rows. 



Anal entire ; 



series of rufous spots; rostral resembling that of Salvador a; series 



of scales 21 rujipunciatus. 



striped; series of scales 19 (17 — 19); slender saurita. 



striped and spotted; series of scales 17 — 21 sirtalis 

 Anal bifid ; 



banded transversely; series of scales 23 — 25 fasciatus. 



transverse bands and spots ; series 29 — 31 taa'isjrilotus. 



transverse bands to uniform ; with suborbitals ; series 27 — 33 



cyclopium. 



irregularly spotted ; series 19 — 21 compressicaudus. 



spots in longitudinal rows ; series 19 kirtlandii. 



striped; orbitals 2—2; series 19 leberis. . 



