A treatise on zoology . r jaw is provided, as a rule, with a series of infra- dentaries. On either side ofthe large paired inferior gularplates a series of lateral gularsextends upwards to the sub-opercular and opercular bones(Fig. 250). The interoper-cular has not been identifiedfor certain. The anteriormedian gular, if present, issmall. On the inner sideof the mandible, the spleniall)ears large teeth, and mayl)e subdivided into severalossicles. Large teeth arealso present above in thevomerine and palatine wall of these teeth tendsto become much folded(p. 285). The paired fins hav
A treatise on zoology . r jaw is provided, as a rule, with a series of infra- dentaries. On either side ofthe large paired inferior gularplates a series of lateral gularsextends upwards to the sub-opercular and opercular bones(Fig. 250). The interoper-cular has not been identifiedfor certain. The anteriormedian gular, if present, issmall. On the inner sideof the mandible, the spleniall)ears large teeth, and mayl)e subdivided into severalossicles. Large teeth arealso present above in thevomerine and palatine wall of these teeth tendsto become much folded(p. 285). The paired fins have anoutstanding scale-covered lobeof considerable size. In some(Holoptychiidae) this centralaxial region is elongate andtape ring,acutely lobate, witha fringe of lepidotrichia oneither side, thus closely re-sembling the fin of Ceratoclus(Fig. 254). Unfortunately,the internal skeleton is un-known in these forms ; but itwould appear to have beenplan, with a jointed central axis bearingIn the Osteolepidae the fins, especi-. FlG. 252. A, eiicloskeleton of tlie second dorsal tin ofGlyptolepis , Ag. B, skeleton of t)ie leftpectoral tin of Enxthciniitcron Ioonl!, Wlit. ; , segment of lonjiitndinal axis ; , basal segmentof axis : h, basal; dermal rays; , postaxialprocess (radial 0; y//./?, preaxial radial; r, railial. built on the mesorachic preaxial and postaxial radials ally the pelvics, are shorter, and less acutely lobate ; in these also the endoskeleton is unknown. The Khizodontidae have lobate fins departing from the mesorachic type : here the preaxial edge and its dermal rays are becoming stronger than the postaxial, as in the Actinopterygii, while the skeletal axis is somewhat posterior (Fig. OSTEOLEPIDOTI 283 258). In this f;imily the endoskeletou is well ossified, and hasbeen described (Trariuair [443], A. S. Woodward [505]). Thepectoral fin has a jointed bony axis of from three to five segments,bearing each a well-developed preaxial radial;
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
