The respiratory epithelium of the rectal tracheal gills of Aeshna cyanea (Muller) larvae is of cellular construction throughout the entire length. It contains numerous tracheoles surrounded by a thin cytoplasmic sheath of tracheoblasts and extracellularly located in deep invaginations of the epithelial cells. The tracheoles run nearly parallel to each other in radial orientation, they are, however, irregularly distributed with respect to their distance from each other and from the cuticle. This arrangement of the tracheoles presumably provides optimum conditions for oxygen uptake.