ptilinum

Etymology
Borrowed from, itself an adaptation of the.

Noun

 * 1)  A bladder-like pouch on the head of schizophoran flies that by expanding enables the fly to emerge from its puparium.
 * 2) * 1980, Stuart E. Reynolds, Integration of Behaviour and Physiology in Ecdysis, Michael J. Berridge, J. E. Treherne, Vincent Brian Wigglesworth, Advances in Insect Physiology, Volume 15, page 500,
 * Certainly, the ptilinum, a special eversible sac on the head which is evidently a "hatching" structure, is instrumental in causing the puparium to crack along its line of weakness, a longitudinal line around the anterior end, which meets a circular line extending around the anterior margin of what was the 4th visible segment of the larvae cuticle (Laing, 1935).
 * Certainly, the ptilinum, a special eversible sac on the head which is evidently a "hatching" structure, is instrumental in causing the puparium to crack along its line of weakness, a longitudinal line around the anterior end, which meets a circular line extending around the anterior margin of what was the 4th visible segment of the larvae cuticle (Laing, 1935).

Translations

 * French: ptiline
 * Latin: ptilīnum