A treatise on zoology . Median longitudinal section of the brain of Acnwnser riithenus. (After , fromSedgwicks Zoology). Cb, cerebellum ; ch, optic cliiasma ; ep, X)ineal body ; hy, pituitary body ;pi, roof of telencephalon with choroid plexus ; M, roof of mesencephalon ; pi, roof of inyelen-cephalon ; , saccus vasculosus ; V, cavity of telencephalon ; z, cavity of Fig. 2S3. Left-side view of brain of A, Adpcnter riitheyuif:; and B, Amic, mh-d. (After Goronowitsch,from Gegenbaur, Vergl. Annt.) ac, auditory nerve ; Kp, epiphysis ; F, facial nerve ; Op, gloss
A treatise on zoology . Median longitudinal section of the brain of Acnwnser riithenus. (After , fromSedgwicks Zoology). Cb, cerebellum ; ch, optic cliiasma ; ep, X)ineal body ; hy, pituitary body ;pi, roof of telencephalon with choroid plexus ; M, roof of mesencephalon ; pi, roof of inyelen-cephalon ; , saccus vasculosus ; V, cavity of telencephalon ; z, cavity of Fig. 2S3. Left-side view of brain of A, Adpcnter riitheyuif:; and B, Amic, mh-d. (After Goronowitsch,from Gegenbaur, Vergl. Annt.) ac, auditory nerve ; Kp, epiphysis ; F, facial nerve ; Op, glosso-pharyngeal nerve ; h and hy, hypophysis ; Hh, cerebellum ; , lobus inferior ; , olfactorylobe; M, mesencephalon ; K, myelencephalon ; o, optic nerve ; pl, choroid plexus ; 7V andTr, trigeminal nerve ; , saccus vasculosus ; Vg, vagus nerve. The urinogenital organs are discussed elsewhere (p. 365); butit may here be mentioned that the cloaca is lost, the anus oj^eningseparately in front, and the genital and urinary ducts lead into a A CTINOP TER YGII 307 einus opening behind. In the Teleostei, however, the sinus maydisappear, all the openings coming to the suiface (Fig. 354). The Actinopterygii tirst appear in early Devonian strata, andhave since become the dominant group of fish. The recentadvances in our knowledge of the structure and classification ofthe more primitive fossils for
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
