52 BULLETIN 154, UNITED STATES NATIONAL MUSEUM 



(lirtVrs from h'vintf<<'(if}ii< in havinji; a scrios of 27 or more f(Mnoral 

 pores on each thigh instead of less than 27.'' Also, the spots on the 

 sides are smaller and nsnally more mnuerous in adult males of 

 leviniscatKs. The lower sides of yonn«^- arvhensis arc spotted, those 

 of young Je/!inJ,sr((tu,s, unsi)()tled. Tlie dorsum of aruhcnsis may be 

 either lined or unlined; if lined, the in'ound color is usually brownish 

 and the lines are wider and more })Oorly defined than is usual in 

 Jemniscatus. 



Description. — Snout moderately pointed; iu)stril usually in suture 

 between anterior and posterior nasal plates; anterior nasal not in 

 contact with second upper labial; supraoculars normally 4; supra- 

 ocular granules usually not extending forward past the anterior 

 border of the fourth supraocular; frontoparietals normally 2; 

 parietals normally 5; anterior and posterior gulars often poorly 

 differentiated, rather small behind, larger in front; anterior gulars 

 often with enlarged central and medio-lateral patches of granules: 

 mesoptychials moderate, uniform or graded so as to be slightly 

 enlarged centrally and smaller toward the extreme lateral edges, in 

 2-6 row^s, posterior not always largest; postmesoptychial granules 

 minute, usually extending forward over the edge of the posterior 

 gular fold. 



Body elongate; ventral plates in 8 (a vestigial outer pair some- 

 times present in addition) large longitudinal series and in 35-42 

 transverse rows; anal spurs often well developed; dorsal granules 

 small; limbs well developed; brachials small, one row larger; ante- 

 brachials 2-3; brachials often in contact with antebrachials, but 

 usually separated from them by granules; postantebrachials gran- 

 ular; postbrachials enlarged, but in continuous series with brachials; 

 f emorals 7-12 ; tibials 2-4 ; femoral pores 27-33 ; tail elongate, taper- 

 ing, with fewer caudal plates than in mnirinus; ventral caudals 

 smooth or weakly keeled; lateral caudals oblique, witli more or less 

 continuous longitudinal keels. 



Coloration moderately variable; lower surfaces white, bluish, or 

 slaty; lower flanks usually darker than median ventral plates; tail 

 brownish, bluish, or olivaceous ; dorsal ground color brownish, bluish 

 or blackish ; sides always w^tli many large round blue spots arranged 

 in more or less regular transverse rows; back of young and females 

 often with four or more wddened, often poorly defined, light lines 

 which tend to disappear with age ; old males without lines ; spots of 

 unlined adults usually extending higher on back tlian those of 

 uvu/rinus. 



°A single spocimpii from British Guiana {liiiniisrdtitx) was r^'ijortcd liy lUitliVL'ii 

 (1915a) as liaving 29 femoral pores. 



