Tracheate: supplied with trachea: a general term applied to all articulates that breathe by means of spiracular openings into a system of tubular structures that extend to all parts of the body.
Tracheation: the arrangement or system of distribution of trachea.
Tracheoles: the capillary trachea of the adult as they develop in masses in the larva: very small, slender tracheae.
Transection: a cut across, at right angles to the body: transverse section.
Transition zone: is the transcontinental belt in which the austral and boreal elements overlap: it is divided into a humid or Alleghanian area; a western arid area; and a Pacific Coast humid area: all of which see.
Transitory: lasting for a short time only.
Translucent: semi-transparent; admitting the passage of light but not of vision.
Translucid: clear: transparent enough to be seen through.
Transparent: so clear as not to obstruct vision.
Transverse: when the longest diameter is across the body.