CRANIAL C'HARAf'TKRS OF LACKRTA JACK.SOXI. 33 



foregoing descriptioii, laeaisured 70 uun. : equal to tlie length of 

 the type .specimen. It is therefore only slightly longer than the 

 >skull of the female which was sacrificed for the sfinie purpose, the 

 length of the latter from snout to vont being 67 mm. Though 

 diffej-ing hy 3 mm. only, the sexual discrepancy in the size of the 

 heads is a striking one : 19 nun. for the uiale against 14 mm. for 

 the female. 



Analogous specimens for sfze in Dr. Peracca's series show 

 corresponding difterences, viz. 20 mm. for the head of a male 

 and 15-5 mm, for a femnle. 



Ventird Plates. — The number of tlie ventral plnte series varies 

 in the Mount Elgon specimens, three of these having 6 longi- 

 tudinal rows only and four of them having 8, which is the same 

 as in the type of the species. 



For the Turin Museum specimens their number is uniformly 

 stated to be 6 ; but to judge from a footnote in connection with 

 this point, the author was fully cognisant of the presence of 

 supplementary series* for some of his specimens, but hesitated to 

 accord them serial rank on account of the inferior size of the scutes 

 which form the outermost rows. 



In several of the Mount Elgon specimens these latter are 

 sufficiently well developed to be considered as a series of venti^als. 



TrauvSversely, the minimum of the plates in the Elgon speci- 

 mens is 23 in an adult male, and the maximum 26 respectively 

 for the male and the female from which the skulls ha.ve been 

 prepared. 



For the Turin Museum series this minimum of 23 occurs in 

 two males, one quite young and the other larger, whereas for 

 the largest and fully adult the number is 24, but the highest 

 figures of 27 and 28 are reached by two females of the same lot ; 

 the first number being identical with that of the Ruwenzori female 

 in the British Museum Collections, whereas the female specimen 

 from Mount Elgon has only 24 rows of these scutes. 



It must be borne in mind that female lizards, having the body 

 more elongate in proportion than the males, usually possess a 

 higher number of transverse series of ventral plates. 



/Scales across the middle of the Body. — These range between 

 38 and 43, giving an average of about 40, the same as recorded 

 for the type specimen, j^rovided we except the male from which 

 the skull was prepared and which showed the abnormally high 

 number of 49. llie Ruwenzori female has 37, a number 

 close to the average of 36 as represented in the Turin Museum 

 series, where they vary between 34 and 38, the latter figure 

 being that also of Lacerta vauereselli, as well a.s constituting 

 the minimum of the British Museum Elgon series of Lacerta 

 jacksoiii. 



Supraciliary granules. — These vary in our specimens, both 

 individually and for the two sides, between 3-3 and 6-5. They 



* Cfr. Dot-.t. M. G. Peraccn.. l\ Ruwcnzon, Relazioni SoientificlK^, vol. i. Zoologia- 

 liotanica. : Rettilicd Aiuiibii, Laoortidae-, pp. 16(5 i lt)7. 



Proc. Zool. So<:.— 1 91 ] . Xo. 111, 3 



