Scale Arrangement on the Throat* (size and shape of the 

 scales) . 



Four variants of scale arrangement are recognized by us: 

 the [median] scales of the throat differ neither in size nor 

 shape from other scales on the throat (Fig. la); the median 

 scales of the throat are sharply enlarged in size on each 

 side of the midline forming longitudinal rows, [thus] differ 

 from the other scales (Fig. lb); the scales of the throat are 

 enlarged, but they are not all the same size (Fig. Ic); 

 intermediate variant between "a" and "b" when the posterior 

 scales of the throat are arranged in two equal rows but very 

 weakly enlarged (Fig. Id). 



Fig. 1. Various arrangements of the throat scales of carpet 

 vipers (explanation in the text). 



Paleoasiatic vipers possess the type "a" scale 

 arrangement on the throat. Of the 235 snakes of this group 

 examined, only three had the type "d" scale arrangements. The 

 throat scales of the African vipers correspond to type "b", 

 rarely "c" and more rarely "d". 



Number of the Dorsal Scales Rows at Midbody. 



According to the values of this character, vipers are 

 divisible into two large groups: (a) vipers with 30 to 40 

 midbody scale rows (and not more than 1.5% of the snakes in 

 this group have 28-29 midbody scale rows), the average number 

 of small scales in the taxonomic groups is not less than 31; 

 and (b) vipers with from 24 to 32 body scale rows - the 

 average number in this group is not more than 31. 



All the Paleoasiatic vipers belong to group "a' 

 all Indian and African snakes belong to group "b". 



whereas 



lower jaw" was used in the original 



