ALLIED TO LACERTA MUEALIS. 35 



the body; pnranal jilate larj^e, bonlered by one semicircle of scales; 11 to 13 femoral 

 pores; a lii^ht vertebral streak usually present. 



Var. ckersonensis. 1 or '1 postnasals and 1 or 2 anterior loreals ; suture between 

 the nasals ^ to f the length of tlie frontonasal, which is often as broad as the 

 internarial space; 38 to 46 scales across the body, usually 40 to 43; praeanal plate 

 large, bordered by one semicircle of scales ; 14 to 18 femoral pores, rarely 13 ; a light 

 vertebral streak usually absent in the adult. 



Var. exigua. Usually 2 jiostnasals ; anterior loreals 1 or 2 or absent : suture between 

 the nasals h to \ the length of the frontonasal, which is usually as broad as the inter- 

 narial space ; 34 to 52 scales across the body, usually 40 to 49 ; praeanal plate usually 

 rather small, bordered by two semicircles of scales, one or two of which, in front of 

 the plate, are often much enlarged and plate-like ; 10 to 20 femoral pores, usually 

 13 to 16 ; a light vertebral streak usually present. 



I should like to emphasize the fact that these forms are not sharply definable, and 

 to express the hope that future writers will refrain from availing themselves of the 

 above characters for the purpose of raising the varieties to the rank of species, as has 

 been done by Schreiber in the analogous case of L. viridis, basing his definitions 

 chiefly on characters first pointed out by me nearly 30 years ago, but leaving out 

 of consideration the numerous exceptions which justify the course 1 have followed. 



I consider L. agili.% and more especially the var. erigna, as the ancestral type from 

 which Z. viridis on the one hand and the species of the Z. mnralis group on the 

 other have been evolved. As regards the latter, the Oriental species with two 

 superposed postnasals are connected with it through L. farm. The other species, 

 with primarily a single postnasal, are separated by a wider gap, which is only partly 

 filled up by L. taurica and L. feloponnesiaca. If I am right, South-Eastern Europe 

 and the neighbouring part of Asia are to be regarded as the centre of origin of 

 tlie existing species of the genus Lacerta. 



How the markings of the striated forms of the L. muralis group can be derived from 

 the more primitive pattern of the young L. agilis, var. exigua, is explained further on, 

 when dealing with L. jmroa. 



Difficulty has often been experienced in distinguishing the Eastern varieties of 

 L. agilis from L. viridis. 1 will, therefore, point out an additional character which 

 does not seem to have received attention before, and by which, except in very rare 

 cases, the correct determination will be ensured. In L. agilis the frontonasal shield is 

 not broader th;ni the internarial space, and is surrounded by three pairs of shields : 

 the nasal, the anterior loreal (or the postnasal), and the prtvfrontal ; in Z. viridis the 

 frontonasal is broader than the internarial space, and is bordered by four or five pairs 

 of shields, both the postnasal and the anterior loreal being nearly always in contact 

 with it, and sometimes also the second loreal. 



Dr. de Bedriaga has stated that the presence of a series of granules between the 



f2 



