47. SISTRURUS 905 



salt solution may be tried. Resort may be had to artificial 

 respiration when respiratory paralysis precedes failure of 

 the circulation. 



Genus 47. Sistrurus 



Crotalus FLEMING, Philos. Zool., Vol. II, 1822, p. 294 (type, C. miliaris) 



(not of Linn.). 



Crotalophorus GRAY, Ann. Philos., 1825, p. 205 (not of Houttuyn). 

 Caudisona FITZINCER, Neue Class. Rept., 1826, p. 34 (type, C.miliarius) 



(not of Laurenti). 

 Sistrurus CARMAN, Mem. Compr. Zool., Cambr., Vol. VIII, No. 3, 



1883, p. no (type, C. miliarius). 



The head is broad and low, with flattened top, and is very 

 distinct from the neck. Its upper surface is covered with 

 nine large plates, the internasals, prefrontals, frontal, supra- 

 oculars, and parietals. The anal plate and most of the 

 urosteges are undivided. The tail is short and ends in a 

 horny rattle or button. The scales are keeled. 



The snakes of this genus differ from the rattlesnakes of 

 the genus Crotalus in having the head covered above with 

 large plates instead of small scales. The few species known 

 are all of small size, and therefore, correspondingly less 

 dangerous than the larger rattlesnakes. One kind has been 

 found in southern Arizona. 



207. Sistrurus catenatus edwardsii (Baird & Girard) 

 EDWARDS MASSASAUGA 



Crotalophorus edwardsii BAIRD & GIRARD, Cat. N. Amer. Rept., Pt. I, 

 Serpents, 1853, p. 15 (type locality, Tamaulipas, Mexico); DUM- 

 ERIL et BIBRON, Erpetol. Gcner., Vol. VII, 1854, p. 1483; BAIRD, 

 U. S. Mex. Bound. Surv., Vol. II, Rept., 1859, p. 15, pi. V, fig. i; 

 BAIRD, Rep. Pac. R. R. Surv., Vol. X, Rept., 1859, pi. XXV, fig. 

 10; DUGES, La Naturaleza, Vol. IV, 1879, p. 27. 



Crotalus edwardsii COPE, Mitch. Res., 1861, p. 125; COUES, Surv. W. 

 looth Merid., Vol. V, 1875, P- 610. 



