no. 3647 PERCIFORM FISHES — GOSLINE 19 



Although, as just mentioned, observations on living brotulids and 

 ophidiids are only preliminary, there are two pieces of circumstantial 

 evidence beyond gross pelvic morphology that suggest these fishes 

 use their pel vies as Urophycis does. One piece of evidence is that the 

 ophidiids, at the expense of considerable elongation of the cleithra, 

 have brought their pelvics forward under the chin and, hence, nearer 

 the mouth. The other is that the brotulids and ophidiids, like Urophycis 

 and gadoids in general, have developed a direct route of innervation 

 for taste perception in the pelvic fins. As Freihofer (1963, p. 141) 

 has noted, in these fishes, the pelvic branch of the ramus lateralis 

 accessorius "passes anterior to the base of the pectoral fin and lateral 

 to the cleithrum and the pectoral actinosts." This does not occur in 

 Gadopsis, which retains the inherited and, for fishes with anterior 

 pelvics, circuitous nerve "route of passing down the postcleithra and 

 then turning and coursing anteriorly en route to the distant pelvic 

 fin" (loc. cit.). 



There is, I believe, a close relationship between the method of 

 locating food by means of pelvic filaments, as noted by Bardach and 

 Case, and the jaw structure of brotulids, ophidiids, Urophycis, and, 

 for that matter, polynemids (which presumably locate food by means 

 of pectoral filaments) . In all of these fishes, the food items are detected 

 under the fish rather than ahead of it, and, in all, the mouth is inferior. 

 In all also, such premaxillary protrusion as occurs extends the upper 

 jaw vertically downward or even downward and slightly backward 

 (rather than forward as in most percoids) ; the premaxillary pedicel 

 is short and vertical, or it even extends up and somewhat forward. 

 Finally, there is a peculiar development of a muscle to the maxillary 

 that Rosen (1964; and in Greenwood, et al., 1966) called a levator 

 maxillae superioris. 



In Merluccius, which differs from most gadoids in having a prog- 

 nathous lower jaw, I can find no "levator maxillae superioris." That 

 some fishes with prognathous lower jaws, however, do have a muscle 

 of this sort is clear from the batrachoid fishes (see Rosen, in Green- 

 wood, et al., 1966). For a further account of this muscle in the cod, 

 see Holmqvist (1910) and van Dobben (1935). 



With regard to senses other than that of taste in the ophidioids, 

 morphological data suggest that the acustico-lateralis system is de- 

 veloped highly, olfaction is normal, and the eyes are degenerate. 



In Gadopsis, as in other ophidioids, the lateralis system of the head 

 lies in enlarged canals that, in the pterotic (fig. 4) and circumorbital 

 bones, are partially or completely open, bony troughs. There is also 

 a large median opening (mucous or sensory pit) without a bony roof 

 on the middorsal line between the two halves of the interorbital 

 commissure. 



