G<S4 NORTH AMERICAN SNAKE.S COPE. 



triangular, and resembles a temporal. The modification is of the same 

 character as that wliich sometimes affects the second superior labial in 

 the A. pisciroruH. 



CROTALOPHORUS Gray. 



Auii. Pbilosopliy, 1825, p. 205; Cat. Brit. Mus., 1849, p. 17 ; Holbrook, N. Amer. Herp., 

 18'12, III, 25; Bd. aud Gird., Cat. Serpt., Smitlis. Inst., 185:!, p. 11 ; Cope, Bull. U. 

 S. Natl. Mils., ;52, 1887, p. G3; Gmelin, Sysf. Nat., 1788, l, 1080 ; ]5oiitiaterre, Ophi- 

 oloj^ic, 17'J0, p. 1; Merreni, Teut. Syst. AiiipliiU., 1820, p. 15G; Boie, Isi*<, 1827, p. 

 5(52. 



Caudisona Fitzinger, Neuc Class. Re.pt., 1826, p. 03 (not of Laurenti, 1708) ; Waj^ler, 

 Nat. Syst. Ainphib., 18;i0, 170; Bonaparte, Saggio,.18:?2, p. 24 ; Gray, Zool. Misc., 

 1842, p. 51 ; Fitziuger, Syst. Rept., 1843, p. 29. 



Sisfriirus Garinan, Mem. Mus. Conipar. Zoology, Cambr, viii, No. 3, p. 118, 1883. 



Tail with a rattle at extremity. Head with nine symmetrical plates 

 above. Nostril between two plates. Urosteges undivided. Scales 

 carina ted. 



This genus, as is immediately perceived, differs from Orotalus only in 

 the possession of the nine cephalic scuta common to most harmless, and 

 the Proteroglyph snakes, and the genera Trigonocephalus aud Ancist- 

 rodon in Crotalidte. The species do not reach so large a size as those 

 of Crotalus, aud they aie hence less dangerous. Their range is also 

 more restricted, since no species is known from South America or Mex- 

 ico south of Vera Cruz, 



Mr. S. W. Garman has nam.ed this genus Sistrurus, on the ground 

 that the name Crotalophorus was preoccupied at the time it was era- 

 ployed by Gray. This does not, however, seem to be the case. It is 

 true that Linuauis uses it instead of Crotalus in the sixth edition of the 

 Systema Naturae (1748, p. 3J), but the system of nomenclature thus 

 adopted is not binomial, so that the names are not authoritative as 

 against later ones. In case Crotalophorus should be adopted from this 

 use of it by Linnseus, it must take precedence of Crotalus of the tenth 

 and later editions. In my opiinon, however, authors have been justified 

 in regarding it as an unused name until applied to the present genus by 

 Dr. J. E. Gray in 1825. 



Three well defined si)ecies are known, which differ as follows : 



Rostral plate wider than high, recurved above; canthus rostralis obscure ; loreal 

 plate separating nasal aud preocular ; head not banded ; dorsal spots few, louger 

 than wide ; rattle nicdiiim C. rmuis.* 



Rostral plate higher than wide, not recurved above; canthus rostralis sharp ; loreal 

 separating nasal and preocular ; rattle minute ; head banded; light stripe, com- 

 mencing at eye ; dorsal spots many C. miliarius. 



Rostral plate higher than wide, not recurved above ; canthus rostralis sharp; nasal 

 and preocular iu contact ; rattle larger ; head bat:ded ; light stripe commencing 

 at nasal plate ; two light stripes below fossa ; donsal spots many C. catenatus 



These three species occupy three distinct regions. The C. ravus be- 

 longs to the Tierra Calieute of eastern Mexico; the C. miliarius to the 



i 



*Caui)ISONA. rava Cope, Proc. Acad. Phila., 1865, p. 191. Mexico. The types came 

 from the State of Vera Cruz and belong to the National Museum. A larger specimen 

 in my private collection came *"rom either the State of Vera Crux or I'uebla. 



