The Terciopelo or Fer-de-Lance is a large snake that can reach lengths up to 250 cm, although the average male ranges between 140 and 180 cm long. The females tend to be longer than males. The body is moderately robust, with a large head, well differentiated and clearly triangular when seen dorsally. The dorsal scales are strongly keeled. The base color is dark gay, brown or olive green, with a distinctive dorsal pattern that consists of a series of triangular designs on both sides of the body, when seen dorsally the designs look like the letter X, which is the reason why in many of its geographic locations it is also known as the X snake. The fer-de-lance is also characterized by the presence of postocular bands on each side of the head. 

The species is viviparous and very fertile, it can give birth to up to 90 offspring. Its high fertility explains why the fer-de-lance is one of the most prominent snakes in the country. Furthermore, this species adapts to perturbed environments, which explains why it is responsible for more than 50% of the ophidic accidents of the region.

The fer-de-lance can be found along the Caribbean, from the northeast of Mexico to Venezuela, and from the Central Pacific in Costa Rica to low lands in the Pacific of Colombia and Ecuador. In Costa Rica, it can be found in abundance in low and wet lands in the Pacific and Caribbean, but the species can be found even at 1500 m of altitude.