HERPETOLOGY OF THE GRAND DUCHY OF BADEN. 55 



ations is in itself a study, and one which deserves in the highest 

 degree the attention of those who have the required leisure and 

 materials at their disposal. In view of the growing interest now 

 justly attached to "variability" in general, it may not be 

 out of place to refer to a few facts of this nature which have 

 struck me in comparing a very limited number of species, and 

 with respect only to one character (that of colour). Generali- 

 sation is not always to be commended in enquiries of this 

 description, but in the present instance it will appear obvious 

 that the universality of the phenomenon becomes more apparent 

 as we extend the field for investigation of this subject, by bringing 

 together larger groups, and by comparing them from more than 

 one point of view. Perhaps in no department more than in 

 Herpetology has this tendency to analogous variability been 

 productive of confusion in nomenclature, by frequently concealing 

 true " specific " characters. 



In the instance of Lacerta agilis hardly any colour-variety can 

 be pointed out which is not "parallel" to others of L. viridis or 

 L. muralis. Thus the uniform brilliant green tint, which covers 

 in rare cases even the head, limbs, and dorsal zone of the male,* 

 — the last parts of the body to undergo this periodical change, — 

 may be said to correspond in L. muralis to the var. elegans, 

 Eimer, or to the var. viridissima, Fitz. of L. viridis. Another 

 variety of the same lizard, not uncommon in Baden, is marked 

 by a profusion of small black dots, greatly resembling the 

 ordinary L. viridis punctata, and suggestive of several types of 

 L. muralis. 



In considering the curious tendency exhibited by various 

 species to offer analogous varieties of this description, it is 

 immaterial to notice whether these varieties are found only 

 sporadically, or whether they have developed into fixed local 

 races ; and further, whether the analogy is permanent or of a 

 merely transitory nature. For it is sometimes more pronounced 

 at certain periods of the year, and in some cases it is only then 

 that its existence strikes the observer. 



In support of this, I may call attention to the significant fact 

 that some males of L. agilis, far from obliterating in spring all 



* Boettger, ' Zoolog. Garten,' 1885, mentions this form of L. agilis as very 

 common near Strasburg. 



