The loreal pit identifies it as a pit viper; from other pit vipers by the presence of large shields instead of uniform small scales on top of head. Body stout, tapering to the anus, neck well marked. Head long and remarkably flat above. Eyes large with vertical pupil and gold flecked iris. Tail short with an elongate terminal shield. Dorsal scales dull and strongly ridged. - JC Daniel The Book of Indian Reptiles and Amphibians.
I found this one high up in the alpine meadows of Sarahan Bushair, Himachal Pradesh, India. Approx elevation of the area is 3400 to 3500 meters. Its habitat consisted of meadows interspersed with rocks and boulders. It was a snake of impressive size for a viper. Though it lacked the distinct head markings of other specimens, the loreal pit clearly indicates it to be a pit viper. The snake vigorously shakes its tail tip (like rattle snake) when handled or nervous. Its defense mechanism also involves spraying of foul odored and bitter tasting liquid, maybe from cloaca. (It had a bulls eyes into my mouth, and it was Yucky).