Sources : Jaculus

Lucan [1st century CE] (Pharsalia, book 9, verse 813-920) : Lo! at a distance on a branchless stump / A jaculus (so named in Libyan clime) / Spat forth his venom which through Paullus' brain / And temples pierced—but had no space to kill. / For fate and death were instant with the wound. / Thus did they know how slowly speeds the bolt / Flung by a sling ; how gentle is the flight / Of Scythian arrows hurtling from the bow. - [Ridley translation, 1919, Volume 2, Page 245]

Pliny the Elder [1st century CE] (Natural History, Book 8, 35): ...that the javelin-snake [iaculum] hurls itself from the branches of trees... - [Rackham translation]

Aelianus [170-230 CE] (On the Characteristics of Animals, Book 6, chapter 18): Indeed one snake launches itself and flies with the speed of a javelin; and its name is derived from its action, for it is called Acontias (the Javelin-snake). - [Scholfield translation]

Gaius Julius Solinus [3rd century CE] (De mirabilibus mundi / Polyhistor, Chapter 27.30): Iaculi climb trees, down from which they whirl with great force, and pierce any animal which happens to be exposed to them. - [Arwen Apps translation, 2011]

Isidore of Seville [7th century CE] (Etymologies, Book 12, 4:29): The iaculus is a flying snake. For they spring up into trees, and whenever some animal happens by they throw [iactare] themselves on it and kill it, whence they are called iaculus [iaculum, “javelin”]. - [Barney, Lewis, et. al. translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Serpents 8.17): As Solinus says, iaculi are serpents, so called because of their own destructiveness. These have wings to fly into the trees and hide; from where they drop to penetrate with great force any animal fortune puts in their way. The serpent is called in the Psalm: 'a flying arrow' [sagitta volans]. - [Badke translation/paraphrase]