A treatise on zoology . yet hon)ocercal, and there are no expanded hypurals. Family Lkptolepidae. Tlie tail is still much as in the scales are cycloid and thin, but ganoine covers both them and thecranial dermal bones. The annular bony centra are pierced by the noto-chord ; the neural arches remain se]iarate from the centra and spines in. Leptolepis duhiiis, Blainv. ; Ujiper Jurassic, Bavaria ; restored, without scales.(After A. S. Woodward.) the abdominal region. There is no median gular. The Leptolepidaeappear in the Trias and die out in the Cretaceous epoch, when themodern Tele
A treatise on zoology . yet hon)ocercal, and there are no expanded hypurals. Family Lkptolepidae. Tlie tail is still much as in the scales are cycloid and thin, but ganoine covers both them and thecranial dermal bones. The annular bony centra are pierced by the noto-chord ; the neural arches remain se]iarate from the centra and spines in. Leptolepis duhiiis, Blainv. ; Ujiper Jurassic, Bavaria ; restored, without scales.(After A. S. Woodward.) the abdominal region. There is no median gular. The Leptolepidaeappear in the Trias and die out in the Cretaceous epoch, when themodern Teleostean types begin to dominate over all others. Leptolcpis, Ag. (Fig. 357) ; Lias to Cretaceous in Europe ; Trias Wales. Aethalion, Miinster ; Euroi^e. Lycoptem, J. ]\I. ; Jurassic,Asia. Thrissops, Ag. ; Jurassic and Cretaceous, Europe. Division B. The tail is truly homocercal, with expanded hypurals, or it isgephyrocercal. The ganoine has vanished, and the centra arealways well ossified and amphicoelous, except in degenerate the hinder region of the dorsal fin is differentiated asan adipose fin (p. 275), in the older families. The scales are of the-cycloid or ctenoid type, or derived therefrom. Group A. Sub-Order CYPRINIFORMES (Ostariophysi). This group is remarkable for the absence of the interorbitalfseptum, which ap
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
