Fig. 3. (A) External view of a spiracle of Cormocephalus elegans. Note the uniform appearance of the ostial trichomes. (B) A tranverse section of the spiracle of C. elegans. Across the ostium (O), the ostial trichomes (OT) are separated from the atrial trichomes (AT) by a denuded cuticular fold (CF). The long atrial trichomes obscure the openings of the tracheae (T) in the atrium (Atr). (C) This external view of the spiracle of C. morsitans shows the elongated tufts of the ostial trichome. The three septa of the Y-shaped atrial valve are visible through the ostium. (D) A tranverse section of the spiracle of C. morsitans. Across the ostium (O), the ostial trichomes (OT) are separated from the atrial trichomes (AT) by the smooth denuded strip of cuticle of the atrial valve (AV). The shorter atrial trichomes leave the openings of tracheae (T) in the atrium (Atr) unobscured and only form a tracheal fimbrium (TF) around each opening. Scale bars, 100 µm.