Herpetology of the grand duchy OF BADEN. 381 



This snake varies individually in temperament, some being 

 unusually pacific, while others are unruly and boisterous. The 

 same might be said of Coronella austriaca, Zamenis viridiflavus, 

 and many others, including Pelias herns, which, according to 

 several writers, is occasionally of very complacent disposition. 

 Amongst lizards a similar diversity prevails : Bell " could not 

 induce" L. viridis to bite his hand, whereas other individuals 

 of this lizard are most violent and irritable without any apparent 

 cause ; L. muralis also often refuses to give vent to those out- 

 bursts of passion to which it is so prone. Such traits are all 

 exemplifications of the common phenomenon of individual varia- 

 tion in characters other than purely external, a sympton of 

 peculiar interest from an evolutionist's point of view. All 

 observers, studying one particular species, lay stress on the 

 distinct natures and idiosyncrasies of separate individuals, 

 pointing out differences which would remain unnoticed by the 

 uninitiated. Instances might be multiplied to show that even 

 with reptiles and amphibians, within their less complex sphere 

 of action and passion, these are so considerable that "quot homines, 

 tot sententice" might almost with equal justice be applied to 

 them. The many records of strange fancies,* of curious 

 sympathies and antipathies, of individual differences in intelli- 

 gence, demeanour, choice of food, &c, are noteworthy as 

 demonstrating the plasticity of the mental nature which is often, 

 no doubt, severely put to the test. 



Similarly, the nervous susceptibility appears subject to an 

 equal variability. This is admirably illustrated in the case of 

 Hyla arborea, some individuals of which are more liable to sudden 

 changes of colouring than others. A singular and somewhat 

 analogous instance with Rana arvalis is given by Leydig.f Every 

 one who has kept numbers of a species under confinement has 

 observed that the single individuals differ in their powers of 

 enduring cold, heat, &c. 



It deserves notice, too, that the locality seems in some 

 degree, as with many higher animals, to influence the psycho- 

 logical constitution. Thus, according to Selys-Longchamps, the 



- ; ' I will only quote the enormity of Bana esculenta, which was observed 

 by a writer in the 'Vienna Ornith. Journal' (Jan., 1887) to seize a swallow 

 resting near the water's edge, and to disappear with its victim into the deep. 



f 'Zool. Anzeiger,' 1885, p. 756. 



