. Bulletin of the British Museum (Natural History), Geology. FISHES OF THE TRIASSIC 267 Genus PHLYCTAENICHTHYS Wade 1935 1935 Phlyctaenichthys Wade: 42. Diagnosis (emended). Skull bones ornamented with tubercles. Posterior parietal triangular, anterior rectangular, bearing short sensory canals in the shape of an inverted "v". Dermopterotic shallow and elongate, bearing long posterior extension of the supraorbital sensory canal. Frontal curved and elongate, separated from orbit edge by dermosphenotic. Opercular bones wider than in Brookvalia, and orientated almost vertically. Preoperc
. Bulletin of the British Museum (Natural History), Geology. FISHES OF THE TRIASSIC 267 Genus PHLYCTAENICHTHYS Wade 1935 1935 Phlyctaenichthys Wade: 42. Diagnosis (emended). Skull bones ornamented with tubercles. Posterior parietal triangular, anterior rectangular, bearing short sensory canals in the shape of an inverted "v". Dermopterotic shallow and elongate, bearing long posterior extension of the supraorbital sensory canal. Frontal curved and elongate, separated from orbit edge by dermosphenotic. Opercular bones wider than in Brookvalia, and orientated almost vertically. Preopercular with no contact with dermopterotic. Six suborbital elements. Maxilla separated from the orbit by narrow infraorbitals. Postrostral present. Lower jaw shorter than upper jaw margin. Body fusiform. Pectoral girdle ornamented with discontinuous, elongate rugae. Scales very deep in lateral line region. Fin rays with many joints. Anal fin small. Dorsal fin with anterior edge lying opposite anterior edge of pelvic fin. Tail hemi- heterocercal, deeply bilobate, with high aspect ratio; anterior rays of dorsal lobe bifurcated twice. Type (and only) species. Phlyctaenichthys pectinatus Wade. Discussion. The outstanding features of this genus are the near vertical suspen- sorium and the presence of numerous suborbitals. The suborbitals are presumably the product of fragmentation of the single suborbital seen in other redfieldiiforms, and possibly also of the anterior part of the preopercular. These two features are probably related. Gardiner (1967) has shown that with the acquisition of a vertical suspensorium in some palaeoniscoid families ( the Aeduelliidae and the Boreoso- midae) the adductor mandibulae probably shifted its origin from the palatoquadrate to the front of the hyomandibular. The pressure of this muscle, together with that of the levator arcus palatini, caused fragmentation of the anterior part of the pre- opercular and of the suborbitals. A less extreme case is s
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