La cert a. 41 



Avith two series ot" scales, one above aud one below, or lower series 

 divided into two. Tail cylindrical, often squarish at the base, 

 thick, t^radually taperinij^ from the base or thinninc^ out in the second 

 tliird or half, 1{ to 1'^, very rarely If times the leni^'th of head 

 and body, but little over one-half of the total leni^th in the very 

 young. 



Nosti'il pierced between two,* three, or four shields. Rostral well 

 separated from the nostril, bent back on the upper surface of the 

 snout, its upper borders sometimes meeting at right angle t ; 

 frontonasal nearly always broader than long, sometimes divided into 

 two by a longitudinal cleft, narrower than the internarial space,J 

 in contact with the upper part of the anterior loreal, hardly ever witli 

 the postnasal § ; suture between the nasals very short, rarely half 

 the lengtii of the frontonasal, soinetimes absent through the rostral 

 forming a narrow suture with the frontonasal || ; prefrontals usually 

 forming an extensive suture, sometimes with an azygos shield 

 between them ; frontal as long as its distance from the rostral or 

 from the end of the snout, 1 j. to 1| times as long as broad, broader 

 behind than the supraoculars, except in the very yoting ; parietals 

 1~J- to 1} times as long as broad, outer border foiming an angular 

 suture with the two upper temporals ; occipital usually shorter (^ to 

 f) than the interparietal, rarely as long, the two shields equal in 

 width or either the one or the other the broader. Four supraoculars, 

 first very small aud in contact with the second loreal,*[ second aud 

 third large, second usually longer than third, fourth small aud in 

 contact with the first upper temporal ** ; 4 to (5 (very rarely 3 or 7) 

 superciliaries, first longest, all in contact with the supraoculars, 



* Only in two specimens (females from Studland aud Lausanne) is the first 

 labial excluded from the nostril, such a condition answering to the definition 

 of the allied genus Nncras. 



t In the female from Studland just mentioned. 



X As broad as the internarial space in a male from Diisseldorf. 



§ Exception is a female from La Roche-eu-Breil, Cote-d'Or, also distinguished 

 by the presence of 4 or 5 granules between the sui^raoculars and the super- 

 ciliaries. In a female from Lausanne the shield is entirely enclosed between 

 the nasals and the prefrontals. 



ll In males from Arlon, Prague, Vienna, in females from Riugwood, Paris, 

 Lyons, Porte, Laiisanne, Mondorf, and in two young from the last locality. 

 In a male from Perliu an azygos shield separates the nasals behind the 

 rostral. 



^ Except in two females from Berlin, in one from Churt, and in a male from 

 La Boiu-boule. Absent on tlie left side in a male from Freiburg, Baden. 



** Exception is a female from Tilford. 



