CROTALUS. 3 



body, and obscures tbe pattern of coloration. External row of scales 

 smooth. The inferior orbital chain is composed of scales nearly as 

 large as the two next rows. 

 Huntingdon Co., Pa. ? 168. 18. 23. 35. 3 J. S. F. Baird. 



In a specimen from Prairie Mer Rouge, La., the general system 

 of coloration is similar; it differs principally in having a reddish 

 brown strip or tint down the back, for a width of some three scales, 

 extending from head to tail. First row of lateral scales smooth. 

 Plates of head as described, except that there are but two plates em- 

 braced between the two postfrontals. The upper jaw pale cream 

 colour, the line of demarcation starting from the anterior canthus, 

 and passing backward to the angle of the mouth, along the edge of 

 the labials, or rather a narrow cream-colored line beginning on the 

 upper labials, at the angle of the mouth, and widening on the fifth 

 plate, encloses the whole anterior portioti of the face below the 

 nostrils. The white patch closely mottled with black beneath the 

 eye. A brown patcb across and beneath the angle of the mouth, in- 

 terrupted by the white just mentioned. 



Prairie Mer Rouge, La. 165. 27. 25. Jas. Fairie. 



Mississiiipi. Col. Wailes. 



2. CrotaluS adamanteus, Beauv. — Head triangular. Two an- 

 terior frontals, connected ■with superciliaries on each side by two large 

 plates : inside of these a second row ; included space filled by small scales. 

 Scales margining superciliaries small ; scattered larger ones toward the 

 centre of the intermediate space. Three rows of scales between the suborbi- 

 tals and labials. Suborbitals extending to the middle of the orbit. Labials 

 15 or 16 above ; 1st, 5th, and 7th largest and vertical ; — below, 18 ; 1st, 4th, 

 and 5th largest. Dorsal rows 27 ; outer rows obsoletely carinated. Three 

 or four dai"k rings on tail. Three series of well-defined perfect rhombs, 

 one dorsal, two lateral, separated by narrow lines. Light stripe from su- 

 perciliary to the angle of the mouth. A second in front of the eye. 



Stn. Crotalus adamanteus, Beauv. Trans. Amer. Pkilos. Soc. IV, 1824, 

 368.— HoLBR. N. Amer. Ilerp. Ill, 1842, 17. PI. ii. 



C. horridus, Hakl. Journ. Acad. Nat. So. Philad. V, ii, 1827, 370. 

 Diamond Rattlesnake. 



Scales on the cheek smooth. Three rather large plates on the 

 edge of tbe upper part of the head, between the superciliaries and 

 rostral, inside of which is a second row of three, also larger than 

 the rest. 



