. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. On some Karroo Fishes from Central Africa. 99. Text-pig. 2.—Ischnolepis bancrofti, Htn. Restoration of posterior part of skull, lateral view. operculum and, superiorly, the supratemporal, and is convex. The bone is pierced, along its posterior border, by the preopercular sensory canal. The operculum is a relatively small, somewhat triangular, plate, with a rounded ventral apex and a dorsal width nearly equal to its height. The upper anterior corner is of uncertain shape, but it is apparently separate
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. On some Karroo Fishes from Central Africa. 99. Text-pig. 2.—Ischnolepis bancrofti, Htn. Restoration of posterior part of skull, lateral view. operculum and, superiorly, the supratemporal, and is convex. The bone is pierced, along its posterior border, by the preopercular sensory canal. The operculum is a relatively small, somewhat triangular, plate, with a rounded ventral apex and a dorsal width nearly equal to its height. The upper anterior corner is of uncertain shape, but it is apparently separated from the preopercular by a small triangular ventral prolongation of the supratemporal, which may be a separate element corresponding to Tra- quair's bone X. The suboperculum is larger than the operculum, and is higher than wide. Its anterior border is concave, its posterior and lower borders convex. The upper border is slightly excavate, so that there is a loose junction between the bone and the oper- culum. The upper anterior corner is acute-angled. Ventrally to the suboperculum is a smaller reniform bone which probably belongs to the , and is here interpreted as an inter operculum. It lies behind the hinder end of the mandible, and has the same internal surface ornamentation of small circular pits as the suboperculum and operculum. The branchiostegal rays undoubtedly passed forward from the lower border of this bone; but no specimen shows them in contact with the bone, although their presence is confirmed by one fragmentary example which is seen in ventral view and which presents, on either side of a median triangular bony mass, a series of four or five overlapping branchiostegal plates lying mesial to the mandible. In his recent paper on "Fossil Fishes from the Karroo System," Brough (, 1931, p. 234) figures the bone which is here described as an interoperculum, but describes it as probably the modified first branchiostegal ray, stating th
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectnaturalhistory, booky
