438 



are black, and in another, dark markings are found on the 

 neck. Replying to my inquiry as to the condition in A. 

 collaris, Mr. Longman informs me that he now suggests that 

 the strikingly white colouration of the specimen may be 

 explained as a case of partial albinism. Melanistic birds are 

 but rarely met with, whereas albinos, on the contrary, are 

 within the experience of everyone. The reverse condition 



appears to obtain in regard to snakes, for Boulenger writes : — 

 < 4 ) "Melanism is frequent in snakes . . . partial albinism 

 is rare; perfect alpinism, characterized by absence of black 

 pigment in the eye, rarer still. "(5) 



Other characters I had relied upon to distinguish the 

 species of Aspidites were the condition and number of the 

 head shields, particular importance being attached to the 

 number of the labial entering the orbit, the sixth being 

 indicative of ,4 . melanocephalus and the seventh of A . 

 ramsayi. Of the five specimens of the latter species now 

 under notice, one conforms to the statement, in two the sixth 



(4) Boulenger : Snakes of Europe, 1913, p. 39. 



(5) For discussion on albinos and white varieties see Waite 

 and others, Zoologist, (3), xv., 1892, and xvi., 1893. 



