. Bulletin of the British Museum (Natural History) Zoology. . Fig. 32 Caudal fin musculature of; A, Polymixia lowei (BMNH : 1-5); B, Percichthys trucha (BMNH : 21-33), showing interradialis connections between medial caudal fin rays. 1969) the relationships of the gadoid families demonstrate a trend toward caudal fin element reduction by fusion that has been accompanied by re-organization and reduction of caudal fin musculature. In gadoids the muscles serving the caudal fin are 'reduced' and simplified compared with those in most other teleosts. Symmons (1979) pointed out tha
. Bulletin of the British Museum (Natural History) Zoology. . Fig. 32 Caudal fin musculature of; A, Polymixia lowei (BMNH : 1-5); B, Percichthys trucha (BMNH : 21-33), showing interradialis connections between medial caudal fin rays. 1969) the relationships of the gadoid families demonstrate a trend toward caudal fin element reduction by fusion that has been accompanied by re-organization and reduction of caudal fin musculature. In gadoids the muscles serving the caudal fin are 'reduced' and simplified compared with those in most other teleosts. Symmons (1979) pointed out that in Gadus hypochordal muscles are lacking and that there are no intrinsic muscles associated with the vertebrae and caudal fin rays other than what she termed a pair of deep dorsal and ventral flexores (which I have referred to as a hypural segment of hypaxial muscle, there being only a dorsal and no ventral component; p. 94). Neither is there a superficial part of the interradialis, a feature common in other teleosts where a sheet of superficial fibres crosses the bases or necks of the caudal rays and so interconnects widely spaced rays. Among some acanthop- terygians the interradialis is often thickened and complex and deeply divided between the upper and lower caudal lobes (see below). In gadoids the interradiales connect only one ray with another and the demarcation between upper and lower regions of the fin is marked by a change of direction of muscle fibres (see above and Fig. 27). Furthermore, interradialis Fig. 33 Macruronus (Macruronus) pinnatus. Holotype, (BMNH : 74). Lateral view of head and anterior body region. NB. Jaws and infraorbitals damaged and anterodorsal part of body torn. muscles occur between the so-called procurrent caudal rays. They are absent between those rays in other teleosts. The longitudinal dorsal and ventral muscles attaching to the upper and lower caudal rays represent what I believe to be merely epaxial and hypaxial muscle bands and a
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