. Bulletin of the Natural History Museum Zoology. . -\ \ \ X -3 ^ l Fig. 2. Distribution of neuromasts types 1 and 2 in A, Melanonus zugmayeri on dorsal surface of head and B, M. gracilis on lateral surface of head. C, innervation pattern of type 1 neuromasts in subnasal region (right side) of M. zugmayeri (dashed lines indicate nerves, arrow heads indicate termination of nerve branch; large arrow points anteriorly). In this and subsequent figures, scale bars in millimetre divisions. oblique row across the lower part of the cheek and a double row across the epioccipital region (Figs 2A,B). The
. Bulletin of the Natural History Museum Zoology. . -\ \ \ X -3 ^ l Fig. 2. Distribution of neuromasts types 1 and 2 in A, Melanonus zugmayeri on dorsal surface of head and B, M. gracilis on lateral surface of head. C, innervation pattern of type 1 neuromasts in subnasal region (right side) of M. zugmayeri (dashed lines indicate nerves, arrow heads indicate termination of nerve branch; large arrow points anteriorly). In this and subsequent figures, scale bars in millimetre divisions. oblique row across the lower part of the cheek and a double row across the epioccipital region (Figs 2A,B). The neuro- masts do not extend backwards on to the body. There are about 500 flange-like neuromasts covering the entire head. Innervation is by the ramus canalis lateralis (Rcl sensu Freihofer, 1970) which exits from the posterior frontal foramen to anastomose through a loose fascia of connective tissue. The neuromasts are innervated by subranches stem- ming from a complex nerve network (Fig. 2C). The Rcl nerve branches from the supraorbital trunk of the trigeminal complex, (Fig. 17), a condition similar to that in Merluccius (Freihofer, 1970). The branch innervating the large posterior neuromasts enclosed in the frontal sensory canal detaches separately from the supraorbital trunk, whereas in Merluccius the nerves separate off together. The large, plate-like neuromasts, housed in the sensory canals number two in the nasal bone, three in the frontal (one beneath the anterior medial ridge, one beneath the lateral arch and one posteriorly), one in the anterior part of the pterotic, one in the parietal, one in each extrascapular, three in the first infraorbital, one in the second, third and fourth, two in the fifth and one in the sixth, and five in the preoperculum. Infraorbitals (Fig. 3). There are six infraorbital bones, the first long and relatively deep with a broadly fretted ventral border, the outer flange which forms the roof to the sensory canal extends as a shelf along the a
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