LACEETA MUEALIS IN WESTEEN EUEOPE AND NOETH AFEICA. 389 



typical form and the spotted or reticulate types of the var. serpa. This is all the more 

 plausihle from the fact that the striated pattern is preserved, in females and young 

 only, in the less divergent types of both the typical form and of the var. serpa. Some 

 specimens of the latter are not at all to be distinguished, so far as markings are 

 concerned, from the var. campestris. Eimer's theory of the derivation of patterns of 

 markings being accepted as correct, we are led to regard the var. campestris as the 

 most ancient form from which the others are descended ; and this, I think, is also 

 supported by the structural characters, which differ less from what we may assume to 

 be the more normal or generalised form of Lacerta before adaptation to climbing 

 petrophilous habits had been reached. The var. campestris has often, and rightly, been 

 compared to such species as L. viridis, L. agilis, and L. taurica. 



De Filippi and De Betta long ago pointed out that, although both the typical 

 form and the var. campestris coexist in the plains of Northern Italy, they keep aloof 

 from each other, the former being a true petrophilous lizard, while the latter has its 

 abode in such localities as are frequented in Central and Northern Europe by L. agilis. 

 According to Lorenz Midler, who has recently published an interesting popular 

 article on these lizards 1 , the Wall-Lizard lives principally on walls and rocks, while 

 the var. campestris (his L. serpa) prefers meadows, borders of woods, and other grassy 

 localities ; he tells us how sharply the territories of both forms are divided in a locality 

 in Piedmont where he had an opportunity of observing them. It was on the road 

 from Baldichiero to Montafia. On one side a steep rock with low prickly vegetation, on 

 the other a grassy border separating the road from cultivated fields. This road forms 

 an absolute boundary between the abodes of the two forms. The var. campestris is a 

 form of the plain, rarely found, in isolated examples, in the mountains, which they 

 exceptionally ascend along grassy valleys. At Imola, in Romagna, De Betta found 

 "le due varieta muralis e campestris conviventi, sulle mura la prima, nella adjacenti 

 campagna la seconda." But in the south of Italy and in Sicily, where both the typical 

 form and the var. campestris have practically disappeared, the var. serpa inhabits 

 indifferently all localities, and runs up the walls and bare cliffs as well as among the 

 grass. 



What the factors are that have preserved the purity of the two races (f. typka and 

 var. campestris) over so great a part of Italy, we do not know, but it is within the 

 limits of direct observation that south of Home a marked distinction between the two 

 has ceased to exist, and this has caused much divergence of opinion among herpe- 

 tologists as to the naming of certain specimens, as I have pointed out below. I am 

 myself inclined to the conclusion that the vars. brueggemanni and nigriventris gradually 

 lead to the southern form, as suggested by Bedriaga, when describing the former, and 

 that, climatic or other conditions having changed, these extremes of the typical form 



1 Blatter 1'. Aq.- u. Tcrr.-Kundc, xiii. Him', pp. L58, L69. 



