96 PROCEEDINGS OF THE NATIONAL MUSEUM vol.66 



&". Width of upper, narrow part of rostral, mea.sured at the level 

 of the suture between internasals and nasals, greater than 

 half the length of suture between anterior nasal and rostral. 



c'. Distance from lower end of suture between upper loreal. 

 and upper preoeular to point of lower preocular 

 wedged in between second and third supralabials 

 equals height of third supralabial ; width of rostral 

 at the -level of the sutui'e between first supralabial and 

 anterior nasal as great as or somewhat greater than 

 the distance from eye to nostril A. blomhoffii. 



c^ Distance from lower end of suture between upper loreal 

 and upper preocular to point of lower preocular, 

 wedged in between second and third supralabials, dis- 

 tinctly less than height of third supralabials ; width 

 of rostrals, at level of suture between first supralabial 

 and anterior nasal, less than distance from eye to nos- 

 tril A, intermedius. 



Nikolski, omitting A. strauchi as not being included in the Russian 

 fauna, amended the key given in the Herpetology of Japan, in the 

 iollowing manner (p. 267, misprints corrected) : 



a\ Ventrals 151, or more. 



h^. Scales in 23-2.5 rows; anterior nasal somewhat larger than pos- 

 terior. 



c^ Subralabials 7 A. halys caucasicus. 



&. Supralabials 8, rarely 7 A, halys halys. 



h'. Scales in 21-23 rows ; anterior nasal at least twice as large as 



posterior A. halys intermedius. 



al Ventrals 151, or less. 



&\ Subcaudals 44 or more A. halys blomhoffii. 



&^ Subcaudals 46 or less A. halys brevicaudus. 



If the specimens, the unquestioned and detailed data of which 

 have been recorded, were plotted on a map of Asia, it would be 

 found that the individuals identified according to the above keys 

 group themselves geographically in such a manner as to justify their 

 recognition nomenclatorially. The number of specimens which devi- 

 ate jrom the normal of each region is not greater than in most other 

 cases of intergrading variable superspecies of wide distribution. 



AGKISTRODON HALYS INTERMEDIUS (Strauch) 



Agkistrodon hJomhofftl intermedius Stejneger, Herp. Japan, Bull. U. S. 



Nat. Mus., No. 58, 1907, p. 464.— Baubour, Proc. New England Zool. Club, 



vol. 4, No. 1909, p. 73 (Mt. Taipaishiang, Shensi). 

 Ancistrodon intenncdiiia Sowerby in Clark and Sowerby, Through Shen- 



Kan, 1912, p. 110 (Shansi). — Bedriaga, Wiss. Res. Przewalski Central- 



Asien Reis., Zool., vol. 3, sect. 1, pt. 4, June 1912, p. 713, pi. 10, figs. 



2-2a, 6-6& (Alashan; Ordos ; Kansu). — Tschugunow, Ann. Mus. Zool. 



St. P§tersbourg, vol. 17, 1913, (p. 255) (Minussinsk). 

 Ancistrodon halys intermedium Nikolski, Fauna Rossij, Rept., vol. 2, 1916, 



p. 276 (Mongolia, Gobi, Ussuri etc.). 



