THE VIPERS 



2607 



Somewhat superior in size to the common viper, this species (A. 

 halys} may be recognized by the small portion of the head that is 

 covered with shields, and also in that each shield, or pair of shields, overlaps with 

 its hinder edge the shield immediately behind it, thus producing a more or less 

 marked imbrication of the whole of the head shields. Another characteristic is to 

 be found in the small size of the anterior frontal shields, which together have a 

 crescentic shape and a somewhat saddle-shaped upper surface. The head is very 

 distinctly defined from the compressed neck, the body being rather long, of a 

 rounded triangular form in the middle, and covered with twenty-three rows of trian- 

 gular scales; the very short tail, which is much thinner than the hinder part of the 



SIBERIAN HAI<YS VIPER. 



(One-half natural size.) 



body, is conical, and armed at the extremity with a forked horny appendage. The 

 ground color of the middle of the back is a dark brownish yellow gray, while that 

 of the under parts is a yellowish white, with more or less well-defined black spots 

 on the hinder shields. The yellow ground of the labial shields of the head has 

 chestnut-brown markings; and the crown of the head bears a large quadrangular 

 blotch, forming an interrupted transverse band on the frontal shields, and a 

 temporal band running from the hinder border of the eye to the angle of the 

 mouth and the side of the neck. Somewhat similar markings ornament the back 

 and are more or less clearly margined with 3 r ellow. Along the whole length of the 

 back and the ridge of the tail are a number of yellowish or yellowish-white black-edged 

 irregular blotches or cross bands; and on the sides are two rows of blackish brown 



