OPHIDIAN GENUS GRAYIA. 



947 



1909.] 



(no. 11) is almost uniform brown above, the darker cross-bars 

 being very indistinct and not forked on the sides. 



Young specimens are very remarkable in showing an inversion 

 of the markings of G. furcata, or rather, as pointed out by 

 Dr. Mocquard, being the negative of what is considered the posi- 

 tive in the adult. The snake may be described as black with 

 light, whitish, or greyish cross-bands (15 to 32 in number), 

 bifurcating on the side. I have long been at a loss to explain 

 how the change takes place, but I have now succeeded in bringing 



Text-fiff. 296. 



AAA 





Side view of bodj' of Gvayla oriiata. 

 Diagrams showing changes in markings with age. 



together enough material of difierent ages to throw satisfactory 

 light on this point. The black ground-colour gradually passes to 

 grey or brown, whilst a black bar develops and enlarges within 

 the light bars of the young, which later become reduced to a 

 naii'ow white margin to the former and finally disappear. The 

 three diagrams (text-fig. 296) will explain the change better than 

 a lengthy description. 



The largest specimen examined by me measures 1030 millim. ; 

 tail 260. 



This species is known from Cameroon, the Gaboon, the Congo, 

 and Angola. 



Proc. Zool. See- -1909, No. LXIV. 64 



