450 BULLETIN 58, UNITED STATES NATIONAL MUSEUM. 



mainland and in North and Central America there is a small compact 

 group consisting of the species A. halys, hlomhqffii and Jiimalayanus 

 occupying the vast territory from the Caspian Sea in the west to the 

 Pacific Ocean in the east, and from Lake Baikal in the north to the 

 Himalayas in the south. They are closel}^ interrelated, in fact so nearly 

 allied that their descent from a common ancestor can not have taken 

 place at a very distant period. Of these, A. hlomhoffii, which is the 

 only species occurring within our limits, shows certain differentia- 

 tions accordmg to locality, making it advisable to discriminate 

 between several forms. 



The Agkistrodon interwedius which Strauch described in 1868 and 

 characterized as an A. hlomhoffii with 23 scale rows, Boidenger, on the 

 other hand, diagnoses as an ^. Jialys without the snout turned up. 

 Practically both seem to be right, for as far as I can see A. inferme- 

 dius, as accepted by them, is not a well-defined form (mvich less a 

 species as this term is used conventionally) , but an aggregation of more 

 or less intermediate specimens. In the sense in which they have 

 been adopted hitherto neither have a definable range. According to 

 Strauch not only does A. hlomhoffii occur in the same localities on the 

 mainland as A. intermedius, but the latter occurs also in Japan pro- 

 miscuously with the former, as individuals with 23 scale rows occur 

 both in southern and northern Japan. The trouble is that the number 

 of scale rows is not constant, the inconstancy apparently varying to 

 some extent with the locality. On the other hand, to what extent the 

 turning up of the end of the snout may serve in all instances as a char- 

 acter to separate A. halys I can not say for lack of material, and for 

 that reason I shall at present treat the latter as a good species. 



For the study of A. intermedius and A. hlomhoffii I have collected 

 about 100 more or less complete scale formulas of individual speci- 

 mens, all of which will be found in the appended tables. 



Table la is a record of 27 specimens of undoubted Japanese origin." 

 They show^ A. hlomhoffii in its purity with a normal scale fornuila of. 

 21 scale rows; 132-146 ventrals (average 141.3); 44-56 pairs of sub- 

 caudals (average 49.2) ; and 7 supralabials. Two of the specimens 

 in the United States National Museum, viz, Nos. 31866 and 34040, 

 have 23 scale rows, and Strauch mentions that in the Leiden Museum 

 he found some specimens from Japan also with 23 scale rows, while 

 Hilgendorf records one of his Tokyo specimens as having 23 rows. 

 On the other hand, the number of supralabials (7) seems to be abso- 

 lutely constant in Japan. 



Table II contains formvilas of 20 specimens from Korea, south- 

 eastern China, and Formosa, viz, 21-23 scale rows; 138-151 ventrals 



« For reasons given farther on (p. 452), I have not included in this table certain 

 specimens in the St. Petersburg Academy Museum, recorded by Strauch as being 

 from Japan. 



