14 ME. G. A. BOULENGER ON LIZARDS 



thus the streaks on the nape are the same in number and position as in the archaic young 



Lacerta, but the vertebral terminates a little beyond the shoulders, and the upper 



lateral streak is present only on the temple ; on the body the latter is absent as such, 



though represented, as in L. jiarva, by a series of spots ; in L. muralis we also can 



trace this series of spots, of which the large blue ocellus so often present above the 



shoulder is one, whilst the lower series is represented by the blue spots on the side 



of the belly ; the median light dorsal streak has vanished in all the members of the 



L. muralis group, except on the nape of certain specimens of L. 'peloponnesiaca *. It 



is clear that, in this case, the vertebral streak on tlie base of the tail is not the 



homologue of that on the nape. That the markings on the nape should be more 



primitive than those on the body, as in L. peloponnesiaca and in the above example 



of Acantliodacti/lus, is fully in accordance with Eimer's law, and it applies also to 



L. ar/ilisf. The scheme given by Mehely J for a uniform nomenclature of what he 



terms "streaks" (li<iht) and "bands" (dark) is correct as regards L. muralis, hut 



does not carry us sufficiently far back to be applicable to all the species of Lnnerta. 



Further, the topographical terms used are open to objection when we consider the 



shifting in position which the so-called " superciliary streak " undergoes in L. agilis, 



or the " parietal band " in certain varieties of L. muralis ^ ; such terms would lead 



to misunderstandings if applied throughout the genus. A glance at text-fig. 5 will 



show that the homologising of the streaks is not so simple a matter as one might 



think at first. 



With the disappearance — the squeezing out, so to speak — of the light vertebral strea]j;, 

 the dark area comprised between the inner dorsal streaks may contract, to form a dark 

 vertebral stripe, broad or narrow, and this is to be found in some specimens of 

 L. ogilis, L. vivipara, L. muralis, etc., thus constituting another series which leads to 

 the breaking up of the stripe into spots and their disappearance. The light spots wliich 

 sometimes appear on the dark bands, as in L. muralis, var. pityusensis, I regard as 

 ■ secondary. The dark light-edged vertebral stripe is the initial form of Eimer's scheme, 

 based on L. muralis ||. According to the theory here propounded, one may distinguisli 

 three grades in the dorsal pattern of striated members of the genus Lacerta, beginning 



* It is a remarkable fact that in all these Lizards, when a light vertebral streak or its representative in 

 the form of spots is present, it never extends beyond the base of the tail, although the dorso-lateral streaks 

 are continued farther back. 



t I know of only one exception to this law in the genus Lacerta, and it is to be found in the aberrant 

 L. echinata. 



t Ann. Mus. Hung. vii. 1909, p. 423, fig. I . 



§ Tr. Zool. Soc. XX. 1913, p. 147, fig. 3. 



II It is surprising that Eimer should have omitted to take AcanihodacUjlas into consideration, if we bear in 

 mind that he suggested regarding the species of that genus as varieties of L. muralis {I. c. pp. 401, 404). As 

 I have already pointed out, the lack of judgment in the appreciation of structural characters detracts much 

 from the value of his otherwise admirable memoir. 



