LACEETA MITRALIS IN WESTERN EUROPE AND NORTH AFRICA. 395 



As regards the coloration, which is highly variable in individuals associating 

 together, the resemblance to var. campestris is, as a rule, greater than to any other 

 form, and some specimens approach the latter so closely that it is not surprising that 

 most authors should have failed to draw a distinction between the two forms. 



The head is often comparatively larger than in the typical form and the var. 

 campestris ; its width is contained once and a half to once and two-thirds in its length ; 

 its depth equals the distance between the anterior border or the centre of the eye and 

 the anterior border of the tympanum ; the snout is obtusely pointed and as long as or 

 a little longer than the postocular part of the head. 



The hind limb reaches the collar, or between the collar and the ear in males, the 

 axilla, the shoulder, or the collar in females ; foot once and one-sixth to once and a 

 half the length of the head. 



The tail is rounded in section and measures once and two-thirds to twice and four- 

 fifths the length of head and body. 



The rostral never enters the nostril and is nearly always separated from the 

 frontonasal by the nasals * ; postnasal single ; frontal as long as its distance from the 

 end of the snout, or shorter ; series of granules between the supraciiiaries and the 

 principal supraoculars rarely complete 2 , the first supraciliary, and sometimes also the 

 second, being in contact with the second supraocular ; parietals once and one-third to 

 once and a half as long as broad, nearly always in contact with the upper postocular 3 ; 

 occipital usually shorter but frequently broader than the interparietal ; temporal scales 

 granular, usually not much larger than the dorsals ; tympanic shield distinct ; 

 masseteric shield usually present 4 , more or less developed, separated from the parietal 

 or from the upper temporal by one to three series of scales ; almost constantly four 

 upper labials anterior to the subocular 5 . 



Collar with even edge (PL XXVIII. fig. 3) or very feebly serrated, composed of 

 7 to 12 (usually 9 to 11) plates ; 25 to 33 scales and granules in a longitudinal series 

 between the symphysis of the chin-shields and the median collar-plate ; gular fold 

 distinct. 



Dorsal scales (PI. XXVIII. fig. 3 a) very small, convex, round or roundish-hexagonal, 

 more or less distinctly keeled, sometimes smaller still and irregularly disposed on 

 the vertebral line; 58 to 77 scales across the middle of the body, usually 62 to 70; 

 '■', and 4, 4, or 4 and 5 transverse series correspond to one ventral plate, 35 to CO 

 to the length of the head. 



Ventral plates in 6 longitudinal and 23 to 30 transverse series. Praeanal plates 

 usually smaller than in the typical form and with two semicircles of small plates. 



' The rostral forms a suture with the frontonasal in a female from Modica and in a male from Rome. 

 3 Two specimens from Procida Id., one from Casamicciola Id., one from Isehia, one from Syracuse. 



3 Exceptions in three specimens from Catania, in two from Lipari Id. (Plate XXVII. figs. 5, 5 a), in one 

 from Giglio Id., in one from Ponza Id., in one from Capri, in one from Pompeii, and in one from Messina. 



4 Absent in two specimens from the Faraglioni, in one from Capri. 



1 Five on each side in one specimen from Pompeii and in one from Messina. 



