ALLIED TO LACEKTA MURALIS. 5 



process of the pra?maxillaiy, as shown in text-fig. 1); reduction in some serirs, 

 increase in otliers, of the osteo-dermal plates. 



3. disappearance of the foramen pavietale. 



4. Disintegration of the head-shields: division of the elements surrounding tlie 

 nostril ; intercalation of granules around the supraocular shields ; multiplication of 

 tlie temporal and labial sliields ; reduction or division of the lower part of the 

 subocular, ultimately excluding it from tlie oral border. 



5. Formation of a transparent disk in tlie lower eyelid, and ultimate fusion of the 

 latter with the upper eyelid. 



fi. Formation of a denticulation or a fringe of scales in front of the ear-opening. 



7. lieductiou or increase in the size of the scales on the body and tail, decrease 

 in the imbrication of the shields on tlie belly, reduction and loss of the collar. 



8. Lengthening and compression of the digits, accompanied by an increase in the 

 number of inferior lamella; ; multiplication of the scales round the digits ; develop- 



Tcxt-fiKUre 1. 



n b. C. 



Upper view of i)remaxill;iry in Larertu rir/ili)i (a), L. vivlp/ira (/>). and L. mvralis {tijpica, Vieuna) (i-), 

 lifter l)e{;i'ii, to show differences in the width of the iiiternariiil space. 



ment of keels on the subdigital himpllie, or of a pectination on one or both sides of 

 the digit. 



9. Lengthening of the tail, perhaps accompanied by an increased fragility of the 

 organ. 



10. Modification of the patterns of markings, starting from striation, leading on the 

 one hand to ocellation (in longitudinal, irregular, or transverse series), on the other to 

 spotting (longitudinal, uregular), reticulation, and barring. Assumption of vivid 

 colours. 



I will now explain how these principles work out when applied to the Lacertidae, 

 and to the species of Laceiia in particular : — 



1. Teeth are present on tlie pterygoids in all members of Sections L and II. of the 

 genus Laccrta, forming a cluster of two or three series in L. aqilis and parva. In 

 Section IV. they persist, constantly or with rare exceptions, in 7>. tauricn, pelopounrsiaca, 

 brandtii, Jccvis, and jayahnri, but disappear in the other species, with rare individual 

 exceptions. They arc usually absent in the other Sections. 



