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JOURNAL, R.A.S. (CEYLON). [VOL. XL 



The head shields of species Nos. 16, 25, 26, 29, 30, and 31 

 all carry the formula a 2 , but I do not mean to say that 

 there are no differences between them : far from it, there 

 may be, and indeed are, many, but I look upon them as too 

 small to be of service in helping the student to identify the 

 several species. 



But although I cannot always carry out my original hopes,. 

 I by no means abandon aiming at them as much as possible. 

 Thus, I do consider that the head shields included under a 

 are really of the Zamenis type, that all the species 

 agree closely with the rat-snake in this particular 

 character. 



On the contrary, I do not pretend that in the column 

 headed " Form" that all forms under a belong to the rat-snake 

 type. I can find no satisfactory classification of this group 

 of forms, and have therefore contented myself with uniting 

 them under some easily understood characters. 



The way in which I have attempted to treat the subject 

 will be best understood by a short analysis of my classifica- 

 tion of each of the parts. 



Form. 



The cobra (No. 45) is undoubtedly the best known snake in 

 Ceylon, and one of the commonest, but as it is rather of an 

 abnormal form I shall take the rat-snake, No. 24, as my type. 



Now, as regards the form of this species (No. 24, Zamenis 

 mucosus) there is nothing remarkable about it. The body 

 is not very elongate, and the head and tail are not distin- 

 guished by any peculiarities in their form or proportions. 

 A general description of its form would read thus : — Body of 

 moderate length, rather slender, sides somewhat compressed, 

 belly flat ; head distinct, with a flat crown and somewhat 

 depressed muzzle ; tail long, cylindrical, tapering to a point. 

 Passing on to more or less closely allied species the differ- 

 ences in these points are endless, and the combinations also. 

 The body may be more cylindrical or more compressed than 

 in the type, the belly flatter, the head more or less distinct, 



