Among the 109 species of gobiids listed at the end, the supratemporals were found in six species: five out of sixteen species in Group 1 and one species in Group 3 (Table 1).No supratemporal was found in Group 2 and Group 4 (for the characteristics of the four groups, see Prince Akihito, 1969). These bones were found between the sensory canal groove of the pterotic and the post-temporal (Fig.1).These species had a continuous sensory canal from the anterior tip of the head to the area of the supratemporals and the supratemporal canal.The supratemporals consisted of three pieces, anterior, median, and posterior, which I named without particular consideration for the homology of Tominaga's (1968: 59) anterior and posterior supratemporals on the Pempheridae.They were all separated in three species, Oxyeleotris marmorata (Figs.1.A and 2.A), Bostrichthys sinensis (Fig.2.C), and Ophiocara porocephala (Fig.2.D), and each piece usually had one nerve foramen.In two species of the genus Butis, B.butis (Fig.2.E, F) and B. gymnopoma (Fig.2.G), the median and posterior supratemporals were fused. In Xenisthmus clarus (Figs.1.B and 2.H) the anterior and median supratemporals were fused.The fused bone had two nerve foramina.Wide individual variations were observed in the shape, including loss of a bone (Fig.2.B), separation of a fused bone, loss of a nerve foramen, or an additional foramen on the upper lateral side.
The presence or absence of supratemporals was dependent on the presence or absence of the sensory canal on that part, except in the cases of Bathygobius petrophilus and Syciopterus japonicus (both belonging to Group 4) which had a continuous sensory canal but no supratemporal canal. Although the presence or absence of sensory canals was sometimes inconsistent, it seems that the systematic value of the supratemporal is signifcant, considering that the most unspecialized Oxyeleotris marmorata and Bostrichthys sinensis (which are the only species having a suborbital) have the most complete sensory canal systems with three supratemporals.
