Figure 1

Sequence of action of the linguo-laryngeal apparatus. a-c. S. camelus . Tongue body (T), apex (A), tongue body base (B), tongue root (R), transverse folds (curved black arrows) and longitudinal folds (dotted lines) of the root, lingual papilla (black *), central lingual papilla (white **), fold between tongue and laryngeal mound (↔), glottis (G), laryngeal projections (black stars), arytenoid cartilage (dotted outline, Ar) which also underlies the lips of the glottis (L). a: Resting position of the tongue and laryngeal mound with an open glottis. b: The glottis is in the closed position. c: The tongue is retracted and covers the rostral portion of the laryngeal mound and lips of the glottis (dotted outline). Note how the lingual papillae hook over the first laryngeal projection. d-f. D. novaehollandiae . Tongue body (T), apex (A), tongue body base (B), lateral (white *) and caudal (white **) lingual papillae, tongue root (R), longitudinal folds (dotted lines) on the floor of the larynx, glottis (G), lips of the glottis (L), protrusion of the lips (white star), arytenoid cartilage (dotted outline, Ar). d: Resting position of the tongue and laryngeal mound with an open glottis. e: The glottis is in the closed position. f: The tongue is retracted and the tongue root covers the rostral portion of the laryngeal mound and lips of the glottis (dotted outline).