A treatise on zoology . reduced, or to disappearentirely, lea\ing the bony layers exposed (Fig. 249). The cranialplates and the lepidotrichia agree in structure with the denticles have not yet been definitely shown to exist. The proximal end of each lepidotrich extends inwards beloAvthe body-scales, just as these overlap each other (p. 210). InOdiolepis the scales o^?erlap the dermal ray to a slight degree, inGljiptolepis for a considerable length, still further in Ghjptopomns,ancl finally, in Holoptychnis the unjointed proximal segment of thelepidotrich is almost as deeply embedde
A treatise on zoology . reduced, or to disappearentirely, lea\ing the bony layers exposed (Fig. 249). The cranialplates and the lepidotrichia agree in structure with the denticles have not yet been definitely shown to exist. The proximal end of each lepidotrich extends inwards beloAvthe body-scales, just as these overlap each other (p. 210). InOdiolepis the scales o^?erlap the dermal ray to a slight degree, inGljiptolepis for a considerable length, still further in Ghjptopomns,ancl finally, in Holoptychnis the unjointed proximal segment of thelepidotrich is almost as deeply embedded as in Dipnoi (p. 232).. The orbit is small and situated far forward. The anteriorcranial liones (premaxillae, nasals, ethmoid, and even frontals andprefrontals) tend to fuse to a continuous shield covering the snout,especially in the Osteolepidae (Figs. 250, 257). It is the presence ofthis shield, sometimes with paired notches below, which leads tothe conclusion that the nostrils were ventral, unlike those of living. Fio. 240. Anterior edge of the dorsal fin of EvMhenopteronFoordi, Wht. jis, base of dermal ray ; r, eudoskeletiilradial; si, scale; .«?, thickened scale-like segment ofanterior dermal ray. OSTEOLEPIDO TI 281
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
