Lacerta. 39 



The series from L. agilis, v. exigua to L. ocellata forms a nearly con- 

 tinuous chain, which there is every reason to regard as representing 9, 

 straight line of evolution, in which lepidosis, size, and coloration go 

 together, proceeding from east to west in the Mediterranean basin, 

 thus affording a highly suggestive example of derivation of forms 

 living simultaneously at the present period. The missing links in the 

 chain find expression in the separation of the three species. 



This suggested line of evolution can, of course, only be postulated 

 by assuming an antiquity for certain existing species which could not 

 be entertained from the standpoint of Mammalian palaeontology. We 

 must, however, bear in mind that while in the Upper Eocene and 

 Miocene times the Placental Mammals were in full process of evolution, 

 the lower Vertebrates had practically come to a standstill, so far as 

 important morphological features are concerned, the only great changes 

 that have since taken place being in their distribution, due in many 

 cases to altered climatic conditions. 



1. LACERTA AGILIS. 

 FOEMA TYPICA. 



Lacerta agilis, part., Linn. Syst. Nat. i, p. 363 (1766) ; Schreib. 

 Herp. Eur. p. 433 (1875). 



Seps argus, Laur. Syn. Eept. pp. 61, 161, pi. i, fig. 5 (1768). 



Seps ruber, Laur. op. cit., pp. 62, 162, pi. iii, fig. 3. 



Sepg caerulescens, Laur. op. cit., pp. 62, 171, pi. i, fig. 3. 



Lacerta pardus, Eazoum. Hist. Nat. Jorat, i, p. 107, pi. i, fig. 3, 

 and pi. ii, fig. 4 (1789). 



Seps stellatus, Schrank, Faun. Boic. i, p. 296 (1798) ; Koch, in 

 Sturm, Deutschl. Faun, iii, H. 6 (1828). 



Lacerta agilis. Wolf, in Sturm, Deutschl. Faun, iii, H. 2 (1799) ; 

 Lichtenst. Verz. Doubl. Mus. Berl. p. 94 (1823) ; Brandt & Eazeb. 

 Med. Zool. pi. xix, fig. 1 (1829) ; Bonap. Icon. Faun. Ital., Eett. Anf. 

 (1836) ; Tschudi, N. Denkschr. AUgem. Schweiz. Nat. Ges. i, 1837, 

 no. 4, p. 21 ; Bell, Brit. Eep. p. 17, figs. (1839) ; Gray, Cat. Liz. 

 p. 32 (1845); Leydig, Deutschl. Saur. p. 197 (1872)"; Bedriaga, 

 Abh. Senckenb. Ges. xiv, 1886, p. 127 ; Bouleng. Cat. Liz. iii, p. 19 

 (1887); Mehely, Beitr. Mon. Kronstadt, Herp. p. 10 (1892) ; Douglass, 

 Herp. Baden, p. 11 (1894) ; Werner, Eept. Amph. Oesterr.-Ung. p. 28 

 (1897) ; Diirigen, Deutschl. Amph. Eept. p. 145, pi. xi, figs. 1-3 

 (1897) ; Leighton, Brit. Liz. p. 55 (1903) ; Schreib. Herp. Eur., ed. 2, 

 p. 473 (1912) ; Bouleng. Tr. Zool. Soc. xxi, 1916, p, 16, pi. i. 



