No. 499] COLORATION OF PLETHODOX 



the varieties erythronotus and cinereus are uncommon, 

 for he says : 



in the collections \f the Smithsonian Institution. The Academy of 

 Natural Sciences and Essex Institute I have observed but four speci- 

 mens of the red-banded variety and four of the -ray which could be 

 regarded as intermediate in character." 



In the material at hand I find that the intermediate 

 individuals, between the varieties just named, are fairly- 

 numerous; so that a series was selected which forms 

 almost an insensible transition from the one to the 

 other. The method here is exactly the reverse of that 

 described above in connection with the red forms ; /'. <■., the 

 red is replaced by brown. In describing the intermediate 

 specimens which he studied, Cope outlined the method 

 which I find carried out in detail in my material. He 

 writes : 



"This [the intermediate character of his specimens] appears in a 

 rufous cast in the dorsal color of the latter [variety cinereus] and a 

 slight obliteration of the borders of the dorsal band in the former 

 [variety erythronotus]." 



The brown of the lateral band in P. c. erythronotus be- 

 gins first to encroach upon the red of the dorsal stripe 

 so that its edges become scalloped (Fig. 3). This 

 spreading of the brown color continues until the dorsal 

 stripe is heavily blotched and the red becomes very dull 

 (Fig. 2). Then the brown blotches gradually coalesce, 

 in consequence of which the red stripe, as such, is 

 obliterated, yet enough of the red pigment remains to 

 give the effect of a dull liver-brown to the back of P. c. 

 cinereus. In a number of specimens of this variety all 

 traces of liver-brown have disappeared, rendering the 

 back uniform in coloration with that of the sides (Fig. 1). 



In respect to structural characteristics no variations 

 were detected except in the case of one red intermediate 

 where only seventeen costal grooves were present. The 

 body proportions of this individual were slightly less 

 than the others. 



