102 I'llOCEEDINGS OF THE ACADEMY OF [Jan., 



American species, and usually about eight in number; five or six 

 rows of scales between supraoculars, often two larger ones in 

 front; four or five rows of scales between the suboculars and upper 

 labials; 29 rows of dorsal scales; ventrals 187-203; subcau- 

 dals 25. 



Length about 1,400 mm. 



Sulphur yellow above; tail lilack or dark brown; dorsal spots 

 chestnut brown, transversely wide and irregularly lozenge shaped, 

 usually lighter in the centres of their lateral parts; these spots are 

 ootnmonly prolonged down to the ventrals; l^elly yellowish, clouded 

 posteriorly; a dark oblique streak behind the eye. 



Hab. — New Mexico, Arizona and Sonora. 



In the size and arrangement of the plates on the muzzle, this 

 species approaches C. durmus of South America. 



Crotalus adamanteus Beauvais. 



Trans. Am. Phil. Soc, IV, 36S (1799); B. and G., I c, 3 ; C. a. ada- 

 manteus Coipe, I. c, 690, and Rep. Nat. ]Mus., 1161 ; C. durissuis^^ 

 Boul., I. c, III, 578; C. adamanteus Stej., I. c, 433. 



Largest of the genus; head broad behind, triangular; rostral 



higher than wide; usually two plates on the muzzle behind the 



nasals, the rest of the head covered with small scales; 6—8 rows 



between supraoculars; 3-5 rows between suboculars and labials; 



^* There has been disagreement as to whether the Linurean name durissus 

 belongs to this or to the South American species. Mr. Boulenger adopts it 

 for this species and uses terrifieus Laur. for the South American. To me 

 the case appears otherwise. Linnajus' scanty description does not sufficiently 

 indicate either, b;it examination of his references, to determine the basis of 

 his species, shows that Ssba's p'ates best indirate the South American form, 

 and in the text (Seba, II, 99) Mexico is the most northern locality referred 

 to. Linncens' paper in the Anicenitates Academiem, I, 500, and Gronovius 

 both treat of specimens from South America ; while the only North Amer- 

 ican rattlesnake apparently known to Kalm was the most northern of all 

 {Jiorr klus Ij.). It appears then that darissns L. is a compound, not of 

 the South American and the diamond rattlesnakes, but of the Ibrmer and 

 the Northern handed species. But Linn;eus' description, ^^ Albo jlavoque 

 'B(iri>is, maculis rhombeis disco (il/nf!,^^ cannot applj' to the latter; durissus, 

 therefore, should bs restricted to tiie South American form. Laurenti's 

 description of terrifieus is not much nmce ample tlian that of Linnreus, but 

 lie refers his species to Seba's PI. 95, fig. 1, in which the only recognizable 

 detail, t'ae scutellation on the muzzle, most clearly indicates the South 

 American species ; terrifieus Laur. is, therefore, a synonym of durissus L.; 

 durissus Laur. is a compound of Linnivus' description, above quoted, and 

 Catcsby's PI. XLI, A'ol. ii, which is horridus. I am unable to find evidence 

 than any of the>e authors knew of the existence of a rattlesnake in North 

 America other than horridus ; and the la'ge diamond rattlesnake of the 

 Gulf States remauied unrecognized until 1799, when Beauvais applied to it 

 the name adaiiui ntcus. 



