126 



Sistrurtis eatenatus, (Raf.). 

 Massasauga; Prairie Rattlesnake. 



Crotalinus eatenatus, Rafinesque, 1818, 80, iv, 41; Crotalus tergemimis, 

 Say, 1823, 14, i, 499; Crotalophorus tergeminus, Holbrook, 1842, 54, iii, 

 29, pi. 5; Caudisona te^'gemina, Wagler, 1830, 75, 176; Sistrunis eaten- 

 atus, Garman, 1883, 13, 176, pi. 9, fig. 2; Caudisona tergemina, Cope, 

 1875, 12, 34 ; Crotalophorus eatenatus, Cope, 18W2, 3, xiv, 684. 



Body stout. Head short. Tail coDstituting from an eighth to one- 

 eleveuth the eutire length. Head covered above with the nine crown- 

 shields usually found in the non-poisonous snakes. Anteorbitals 2, the 

 upper horizontally elongated, joining the prefrontal and excluding there- 

 from the small triangular loral. Lower anteorbital narrow and long, 

 forming a part of the boundary of the pit. Supraorbitals large and over- 

 hanging the eyes. Upper labials 11 to 14, excluded from the boundary 

 of the orbit. Lower labials 12, small. Scales in 25, rarely 23, rows, all 

 strongly keeled, except those of the outer row. Ventral plates 136 to 

 153. Subcaudals 21 to 29, a few of the most posterior divided. 



The ground color varies from light ashy, often with a reddish tinge, 

 through ashy brown to deep brown and even black ; below from yellow- 

 ish, sprinkled with dusky, to slate blue, mingled with yellowish white 

 and black. There are above, seven series of dark spots, which are vari- 

 able in intensity of color from chestnut-brown to black. When the 

 ground color is very dark the spots may disappear, and we see then a uni- 

 formly black snake. The outer borders of the spots are usually darker 

 than the centers, and are surrounded with a narrow line of paler. The 

 spots of the successive rows alternate. Those of the median, or dorsal, 

 series are from 35 to 48 in number, and descend on each side to about 

 the eighth row of scales. They are broader than long, and in the median 

 line are notched in front and behind. Occasionally they may be wholly 

 divided. Just below this series is another of much smaller spots. Fur- 

 ther out is a series of spots which extend from the second to the sixth 

 row of scales. The lowest series on each side lies on the outer ends of 

 the ventral plates and the three outer rows of scales. Each side of the 

 head with a broad, dark band from the eye back on the neck. This is 

 bounded below by a streak of yellowish white from the pit to the corner 

 of the mouth and on the neck. Upper labials mostly dusky. Upper 

 surface of the head with two dark, longitudinal streaks and three paler 

 ones. Lower jaw variegated with yellowish white and dusky. A pale 

 transverse band from eye to eye, bordered with darker. The length may 

 reach three feet in fully grown specimens. 



Ohio and Michigan to Utah. Said by Garman to extend to Missis- 

 sippi, on what authority I do not know. In Indiana it is abundant in 



