. Bulletin of the British Museum (Natural History) Zoology. PHARYNGOBRANCHIAL ORGAN OF MUGILID FISHES 119 posterior margin. ., cut iL medial surface ec 5 teeth m A, Agonostomus sp. (BMNH 18: 22-37, ca. 35 mm SL), ventral view of toothplates, all teeth are of the B & C, Chaenomugil proboscideus (BMNH 15: 278-9, 56 mm SL); B shows anterior tip of pharyngobranchial 3 bearing teeth; C shows part of a row of distal-type teeth on pharyngobranchial 4 toothplate, the epithelial cushion has been cut away to expose shafts of
. Bulletin of the British Museum (Natural History) Zoology. PHARYNGOBRANCHIAL ORGAN OF MUGILID FISHES 119 posterior margin. ., cut iL medial surface ec 5 teeth m A, Agonostomus sp. (BMNH 18: 22-37, ca. 35 mm SL), ventral view of toothplates, all teeth are of the B & C, Chaenomugil proboscideus (BMNH 15: 278-9, 56 mm SL); B shows anterior tip of pharyngobranchial 3 bearing teeth; C shows part of a row of distal-type teeth on pharyngobranchial 4 toothplate, the epithelial cushion has been cut away to expose shafts of lateral teeth. , teeth stemming from the free lateral margin of the toothplate. B & C viewed ventrolateral^. Scale = mm. At 19-23 mm SL the skeletal elements, including the core of the 1st pharyngobranchial, are well ossified. The dorsal keel of the 3rd pharyngobranchial and the lateral and medial articular processes of both the 3rd pharyngobranchial and 4th toothplate enlarge. The anterior lip of the 4th toothplate elevates to contact the surface of the lateral articular process rising from the 3rd pharyngobranchial. The teeth are characteristically of the distal-type on the lateral part of the 3rd pharyngobranchial toothplate and entirely so on the 4th which expands and lengthens to more than half the length of the 3rd. At 28 mm SL the 4th toothplate is distinctly broadened and its length usually equals that of the 3rd. Both are covered principally by distal-type teeth although a few proximal-types may remain on their medial borders. At a later stage (36 mm L. saliens, Fig. 9D) the adult pharyngobranchial characteris- tics are developed. The lateral process, articulating with the 3rd epibranchial, is now positioned centrally due to the lateral expansion of the toothplate. The 'lip' of the 4th toothplate border is now a thin lamina adpressed to the lateral and part of the medial processes of the 3rd pharyngobranchial. Later, as the medial process extends further po
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