. Bulletin of the British Museum (Natural History) Zoology. Fig. 17 PBO of A, Mwg/7 /zos/?es (BMNH : 1-2, mm SL); B, M. thobumi (: 170-1, 153 mm SL). Lateral views of right side. former, the narrower the latter (eg., Mugilhospes, Neomyxus leuciscus). An extensive sulcus may not, however, indicate the plesiomorphic state since in those taxa with wide sulci (eg. Liza haematocheilus) the length of the entire PBO is in- creased due to the increased distance between the 2nd and 3rd epibranchials. Considering first the genera exhibiting the more derived condition (ie., those
. Bulletin of the British Museum (Natural History) Zoology. Fig. 17 PBO of A, Mwg/7 /zos/?es (BMNH : 1-2, mm SL); B, M. thobumi (: 170-1, 153 mm SL). Lateral views of right side. former, the narrower the latter (eg., Mugilhospes, Neomyxus leuciscus). An extensive sulcus may not, however, indicate the plesiomorphic state since in those taxa with wide sulci (eg. Liza haematocheilus) the length of the entire PBO is in- creased due to the increased distance between the 2nd and 3rd epibranchials. Considering first the genera exhibiting the more derived condition (ie., those above node 5 on Fig. 20), Myxus has a PBO morphology similar to that of some Mugil species, but differs from these and other mugilids in its convex denticulate sulcus border. We follow Ingham (1952) in including Trachy- stoma petardi in the genus since its PBO morphotype and jaw dentition are nearly identical to those of the type species M. elongatus. Schultz (1946) included in Trachystoma, Mugil capensis Cuv. & Val., 1836 (= M. euronotus A. Smith, as given in Schultz). However, Mugil capensis is unlike the other two species in both the form of its PBO and its jaws, the former resembling more closely that of Mugil cephalus, the latter those of Mugil curvidens. Neomyxus shares PBO characters (extensive denticulate area, vertical and narrow sulcus) with Mugil hospes. Thought by Schultz (1946) and Ingham (1952) to be closely related to Chaenomugil, it differs considerably from this taxon in PBO morphology (see p. 124) and lower jaw shape. Although the lower lip of Chaenomugil is dependent as in Neomyxus, the labial teeth are bicuspid, short, and somewhat posteriorly directed. Chelon has a similar PBO morphology to some Liza species in possessing two valves, but the upper of these is highly papillose (cf. the lower in Liza). Schultz (1946) unjustifiably synonymised Liza and Oedalechilus with Chelon; Oedalechilus, as represented by the type species Mugil labeo Cuvier, was though
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