HERPETOLOGY OF JAPAN. 447 



situated under the eye antl separated by a single row of scales; four 

 lower labials in contact with anterior chin-shields which are much 

 larger than the posterior; 21 rows of scales, all except outer row 

 keeled and with two apical pits; 146 ventrals; anal entire; sub- 

 caudals in pairs, 22+ (tail defective). Color (in alcohol) above 

 tawny-olive with a brownish black, very distinct zigzag band along 

 the middle of back and tail, and a series of obscure, alternating, 

 lateral spots; top of head brownisli black continuous with a similarly 

 colored chevron mark opening backward on occiput; a brownish 

 black band from nostril through eye over lower temporals to the side 

 of neck passing over the last supralabial at angle of mouth; canthus 

 rostralis and supralabials yellowish, the latter mostl}" with a black line 

 along the posterior suture; chin and throat yellowish, mottled with 

 dark slate color; whole underside uniform slate black, each ventral 

 narrowly edged with pale olive. 



Dimensions. 



■mm. 



Total length (tail defective) 568 



Snout to vent 520 



The proportion of tail to total length in the female averages as 1 to 

 9.33. 



In the male the tail is considerably longer, with more numerous 

 subcaudals, the proportion to total length averaging as 1 to 7.33. 



The viper very rarely exceeds 700 mm. in total length. 



Variation. — The specimen described above represents the average 

 of this species, but both scutellation and coloration are very variable. 

 The degree of breaking up of the normal shields of the head is thus 

 very different in different individuals, so that two specimens exactly 

 alike can rarely be found; thus the frontal may be in contact with 

 the supraoculars, or on the other hand it may be separated from the 

 parietals by a series of scales; number of scales around the eye varies 

 between 6 and 13, of supralabials between 6 and 10. The variation 

 in nunvber of ventrals and its correlation with the geographical dis- 

 tribution has been alluded to above (p. 446). 



The coloration is also exceedingly variable, at least in European 

 specimens, the ground color varying through all the shades of brown 

 and olive from silvery gray to black, and the pattern showing endless 

 modifications of the one described above which may be said to be 

 typical. 



Habitat. — The common viper extends from western Europe to the 

 Japanese and Okhotsk seas in the East. 



Numerous specimens were collected in the island of Sakhalin by 

 Prof. F. Schmidt, in 1863. Nikolski says that this snake is very com- 

 mon on the island, that Dobrotvorski noted it in the southern part and 

 that Poljakof collected a specimen in the neighborhood of Korsakovski. 



