1140 REPORT OF NATIONAL MUSEUM, 1898. 



SISTRURUS Garman. 



Sistruriis Garj^a-n, N. Ainer. Reptiles, 1883, p. 110; Science, XIX, 1892, p. 290.— 

 Stejnegeh, Report U. S. Nut. JNIus., 1893 (189.5), p. 410.— W. E. Taylor' 

 Amer. Nat., 1895, p. 283.— Boulengkk, Cat. Suakes Brit. Mus.,2ded., Ill, 1896, 

 p. 569. 



Crotalus LiNN.Kns, part, Syst. Nat., 12th ed., 1766, p. 372. — Gmelin, Linnaeus Syst. 

 Nat., I, 1788, p. 1080.— BONNATEUHE, Ophiologie, 1790, p. 1.— Merrem, Tent. 

 Syst. Amphib., 1820, p. 156.— BoiE, Isis von Okeu, 1827, p. 562. 



Croialophorus Gray, Ann. Philosophy, 1825, p. 205 ; not of Linn;pu8 nor Honttuyn ; 

 Cat. Brit. Mus., 1849, p. 17.— Holbrook, N. Amer. Herp., Ill, 1842, p.25.— 

 Baihd and Gikard, Cat. N. Amer. Rept., Pt. 1, Serp., 1853, p. 11. 



Caiidisona Fitzingek, Nene Class. Rept., 1820, p. 63. — Wagler, Nat. Syst. 

 Amphib., 1830, p. 176. — Bonaparte, Saggio, 1832, p. 24.— Gray, Zool. Misc., 

 1842, p. 51.— FiTZiNGER, Syst. Rept., 1843, p. 29. 



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

 above, Nostril between two plates. Urosteges undivided. Scales 

 carinated. 



This genus, as is immediately perceived, differs from Crotalus only 

 in the possession of the nine cephalic scuta common to most harmless 

 snakes, the Proteroglypha, and tlie genera Trujonocephalns and 

 Ancistrodon in Crotalidte. The species do not reach so large a size 

 as those of Crotalus, and they are hence less dangerous. Their range 

 is also more restricted, since no species is known from South America 

 or Mexico south of Vera Cruz. 



Three well-defined species are known, which differ as follows: 

 Rostral plate wider than high, recnrved above; canthns rostralis ohscnre; loreal 

 separating nasal and preocular; head not banded; dorsal spots few, longer than 



wide ; rather medinm -S'. ravus. ' 



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

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

 mencing at eye ; dorsal spots, many *S'. tniliarius. 



Rostral plate higher than w^ide, not recurved above; canthus rostralis sharp; nasal 

 and preocular in contact; rattle larger; head ])auded; light stripe beginning at 

 nasal plate; two light strijies below fossa; dorsal spots, many S. catenatus. 



These tliree species occupy three distinct regions. The S. ravus 

 belongs to the Tier r a Oaliente of eastern Mexico; the S. miliarius to 

 the Austroriparian region of North America, and the 8. catenatus to the 

 eastern region, except that part of it that lies east of the Alleghany 



' Caudisona rava Cope, Proc. Acad. Nat. Sci. Phila., 1865, p. 191. The types came from 

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

 my private collection came from either the State of Vera Cruz or Puebla (Proc. 

 Amer. Phil. Soc, XXII, 1885, p. 382). The frontal plate is narrowed behind, and tiie 

 parietals are about the size of the superciliarie.s. Rows of scales, 21 ; superior 

 labials, 12; gastrosteges, 144; urosteges, 28. There are but twenty-six spots on the 

 middle line of the body ; they are parallelogrannnic, or longer than wide. A single 

 rounded spot is opposite each of them on the sides; no alternates. Belly clouded 

 on the end of the gastrosteges. Head uniform light brown, with only a brown spot 

 on each side the nape. 



Measurements. — Length, ,567 mm.; tail, 45; rattle, 12 mm., with seven joints and a 

 button. In the tyi)es there are twenty- three rows of scales. 



