The Jaculus, (pl. jaculi, meaning "thrown" in Latin) is a small mythical serpent or dragon. It can be shown with wings and sometimes has front legs. It is also sometimes known as the javelin snake. It was said that the jaculus hid in the trees and sprang out at its victims. The force of it launching itself at the victim led to the association with javelins.
Pliny the Elder described it as follows: "The jaculus darts from the branches of trees; and it is not only to our feet that the serpent is formidable, for these fly through the air even, just as though they were hurled from an engine."
Lucan also describes the attack of the jaculus in the Pharsalia. He explains that it is the wound caused by the jaculus hitting the victim that causes death. The jaculus does not kill with venom. Jaculus is also found in the Old Norse romance Yngvars saga viðfǫrla. Here it is actually said to be an extremely large dragon (dreki).
In 1986, Domergue discovered a new snake: Ithycyphus perineti. The snake was very similar to the jaculus; it falls from a tree like a spear to stab animals. It has V-shaped markings that resemble a spear head. The snake is known as "fandrefiala snake".