Photograph of Blacktail Rattlesnake

-- The heavy-bodied Blacktail Rattlesnake is most frequently encountered in rough and rugged mountain canyons and hillsides, though it is sometimes found crossing the flatland separating rocky areas. A series of very dark blotches are found down the back of the Blacktail Rattlesnake, with the posteriormost blotches forming crossbands. The background color can be extremely variable, ranging from yellowish tan or olive to gray or dark brown. The all-black tail is striking, and the black velvet color begins immediately at the vent and covers the entire tail. The top or crown of the head is often dark brown or black and contrasts with the tan or yellow coloration of the rest of the head. A chocolate brown ocular stripe runs through the eye into the corner of the mouth. An adult C. molossus may measure 76-109 cm 30-42 in , although they may grow larger than 125 cm 49 in . The rough and keeled dorsal scales may be in 25-29 scale rows at midbody and the anal plate is undivided