b 



HERPETOLOGY OF JAPAN. 449 



seen from the accoinpanyiiig cut (fig. 361) that if the latter bone 

 (a) be moved forward or backward, the maxillary {d) hinges on the 

 lachrymal (prefrontal) {e) and that if the ectopterygoid be pushed 

 forward the fang is erected. 



For a more detailed description of the poison apparatus, the poison, 

 etc., see my Poisonous Snakes of 

 North America.* 



, The Crotalid snakes are found 

 in both hemispheres. They are 

 entirely absent, however, in Africa 

 aild the southwestern corner of 

 Asia, as well as in Australia. 



The}" are practically unknown in *, ^^=^-^ (JL 



Europe also, except that one spe- 

 cies enters the extreme south- 

 eastern corner. 



. . Fig. 361.— Poison apparatus of a Ce-otalid 



Ihe general impression that snake, right side, a, external pterygoid 

 the Crotalidse are overwhelmingly ^^ (ectopterygoid or transpalatine); 6, 



_*=_'' internal ptery'goid bone (entoptery-goid) ; 



American in their distribution is c, palatal bone; (f, maxillary bone; e,LACHRY- 



,•1 1 ,in MAL bone (prefrontal). (AfTER MITCHELL.) 



Gn tirely erroneo LIS , as nearly 40 per 



cent of the known species occur in Asia, and I am strongly of the 

 opinion that the family originated in the Old World and spread to 

 America afterward. The rattlesnakes which are peculiar to the 

 latter continent are the latest specialization of the type. 



KEY TO r\PANESE GENERA OF CROTALID.E. 



a} Top of head with large symmt trical shields Agkistrodon, p. 449. 



a^ Top of head covered with scale s Tmneresurns, p. 465. 



Genus AGKISTRODON & Beauvois. 



1799. Agkistrodon Beauvois, Trans. Amer. Philos. Soc, IV, p. 381 (type, A. 

 mokasen). 



1802. Scytale Latreille, Hist. Nat. Rept., Ill, p. 158 (same type). 



1803. Cenchris Daudin, Bull. Soc. Fhilom. (Paris), III, No. 72, March 1803, p. 188 



(same type). 

 1819. Scytalus Rafinesque, Am. Journ. Sci., I, p. 84 (emendation). 

 1826. Tisiphone Fitzinger, Neue Class. Rept., pp. 34, 63 (type, T. cuprea). 

 1826. Trigonocephalus Boie, Isis, 1826, p. 214 (not of Oppel, 1811). 

 1836. Acontias Troost, Ann. Lye. Nat. Hist. N. Y., Ill, p. 190 (type, A. leuco- 



stoma; not of Cuvier, 1829). 

 1836. Toxicophis Troost, Ann. Lye. Nat. Hist. N. Y., Ill, p. 190 (same type). 

 1849. Halys Gray, Cat. Snakes Brit. Mus., p. 14 (type, Trigonocephalus halys Boie; 



not of Fabricius, 1803). 

 1854. Ancistrodon Baird, Serp. N. Y., p. 13 (emendation) (not of Roemer, 1849). 



Among the species of the genus Aghistrodon which extends from the 

 northern borders of the Caspian Sea throughout most of the Asiatic 



a Rept. U. S. Nat. Mus. for 1893, pp. 365-380 and 457-480. 



&From ayKidrpov, hook; 68(hv, tooth. The correct transliteration would be 

 Andstrodon. 



26485— No. 58—07 29 



