. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates. 208 COMPARATIVE ANATOMY stages of Teleosts. A large, paired, dorsal lobe is present n the In Petromyzon the pineal apparatus is represented by t\\" vesicles, which arc probably the displaced members of a pair, each connected with the dorsal surface of the diencephalon (ganglion habenulre) and lying one above the other just beneath the roof of the skull : the integument immediately above these vesicles is pigmentless. The cells on the ventral side of the larger dorsal vesicle (epipkysis OY pineal oryan—proba
. Comparative anatomy of vertebrates. Anatomy, Comparative; Vertebrates. 208 COMPARATIVE ANATOMY stages of Teleosts. A large, paired, dorsal lobe is present n the In Petromyzon the pineal apparatus is represented by t\\" vesicles, which arc probably the displaced members of a pair, each connected with the dorsal surface of the diencephalon (ganglion habenulre) and lying one above the other just beneath the roof of the skull : the integument immediately above these vesicles is pigmentless. The cells on the ventral side of the larger dorsal vesicle (epipkysis OY pineal oryan—probably representing the organ of the right side) are arranged radially and contain pigment, form-. Tz&zzm&z " PeUucn'n - %##?, "Rctiiin" -i&£f£W- '4 ' , tff " PilJi'fiiJn" ~ " Retiii» ' Parapineal Fin. 156.—TRANSVERSE SECTION OF PINEAL APPARATUS OF Petromy~on (After Studnicka.) The connective tissue roof of the skull (.«) is seen above, the roof of the third ventricle (di) below. ing a kind of retina, but they show signs of degeneration ; the lower vesicle or parapineal (left) or^cm, which probably corresponds to the parietal organ of Lizards () is simpler and more variable, and is without pigment. The pineal stalk, arising just in front of the posterior commissure, passes directly into the dorsal vesicle, and the ventral vesicle is also connected with the roof of the diencephalon (habenular ganglion) by a stalk. In Myxinoids the pineal apparatus is evidently much degenerated, and nothing is known of an epiphysis Elasmobranchs.—The brain of these Fishes, like that of Cyclostomes, is in many respects of a specialised form, character- The homology of the parts as given above has recently been questioned : it is possible that the division described as the telencephalon corresponds to the diencephalon, and that the " cerebellum " belongs to the mid-brain. - For the hypophysis of Cyclostomes, see under Olfactory
Size: 1680px × 1488px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectanatomycomparative
