HERPETOLOGY OF THE GRAND DUCHY OF BADEN. 57 



Of still more general nature may be mentioned the frequent 

 appearance, in very many reptiles, of melanotic varieties. 

 Another example is the widespread tendency for morphologically 

 corresponding parts to be marked in a similar manner. Thus 

 attention has been drawn (Ley dig, ' Pigment e der Haut-decke,' 

 p. 17) to the dark streak which in many amphibia runs from 

 the nasal opening through the eyes, and is likewise perceivable 

 in some ophidians.* Another case in point is the bright yellow 

 colouring which is seen on the hind legs of many of our Ranidce 

 (its entire absence with R. ridibunda is a distinguishing feature 

 of that species) ; the reproduction of blue or black spots on the 

 outer ventral plates, common to all four of the German Lacertidce, 

 or the V-shaped mark on the shoulders of many anurous 

 batrachians may be also mentioned. The formation of the last- 

 named feature can be traced, in all species which possess it, to 

 the breaking-up of the lateral lines into oval spots, which, when 

 they coalesce at the back of the head (though this is not uni- 

 versally the case), produce this figure. 



But, though the development of these markings may have 

 been identical, their existence is less a sign of close affinity than 

 of an inherited tendency to vary in an analogous manner ; a fact 

 which is demonstrated still more clearly in the rarer cases of 

 structural variability of this kind. 



A reference to any work which enumerates the varieties of the 

 Keptilia and Amphibia will show that the number of such 

 instances could be multiplied ad infinitum, and will serve at the 

 same time to illustrate the principle firmly established, that 

 "Nature is prodigal in variety, but niggardly in innovation." 



A number of Sand Lizards from extensive tracts of wood in 

 Baden, and from the large Bienwald on the other side of 

 the Bhine, were very uniform in their coloration. This circum- 

 stance at first led me to suspect a connection between the locality 



* The importance attached by some zoologists to markings, even as 

 characteristic as these often are, as something inoculated into the constitu- 

 tion, and hence unalterable, appears often exaggerated. With birds they 

 are frequently of great value ; with reptiles, and still more in the case of 

 batrachians, their stability is easily overrated, and in the cases here named 

 the markings, or special colours, however frequent, are not constant characters 

 in the species which exhibit them. 



ZOOLOGIST. — FEB. 1891. F 



