Text-book of comparative anatomy

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Identifier: textbookofcompar01lang (find matches)
Title: Text-book of comparative anatomy
Year: 1898 (1890s)
Authors: Lang, Arnold, 1855-1914 Bernard, Henry Meyners Bernard, Matilda Haeckel, Ernst Heinrich Philipp August, 1834-1919
Subjects: Anatomy, Comparative
Publisher: London, New York, Macmillan and Co.
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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rois, Keller, Heider, Marshall, Lenden- feld, Gotte, etc. CLASS III.—Cnidaria. Systematic Review. Sub-Class 1. Hydrozoa. Prototype: Hydropolyp or Hydruht. In all Hydrozoa an ectodermal oeso-phagus is wanting ; the mouth leads direct into the endodermal gastric cavity. Gastralfilaments are wanting. The sexual products mostly arise from the ectoderm. Thesexes are generally separate. II CNID ARIA 6 Order 1. Hydridae Fresh-water polyps . Single individuals or small stocks without envelopes consisting of a few similarindividuals. Reproduction asexual by gemination, and sexual. Hydra develop directfrom the egg. Hermaphrodite. Hydra, in fresh water. Order 2. Hydromedusse. Hydroid colonies, which are at least dimorphic, since, besides the sterile nutritivepolyps, there arise by gemmation sexual persons, which either detach themselves asCmspct?ufc. M.dasce and swim about freely, or remain united with the colony asmedusoid gonophores. In one series of Hydromedusce the attached Hydroid form is
Text Appearing After Image:
FIG. ti-1—Bougainvillea ramosa (after Allman), with budding Meduss. li, Nutritive polyps;mk, Medusa buds ; m, detached young Medusa (Maryclis ramosa). suppressed, as the Cmspedotc Medusa develops direct from the fertilised egg intoanother Medusa. The systematic relationship of single forms is naturally determinedboth by the Hydroid and by the Medusa forms. As the whole life-history anddevelopment of only a minority of the many species is available, and in many speciesonly the Hydroid form is known, in others only the Medusa form, a natural systemof the Hydromedusce is still a desideratum. Hydroid form. Medusa form. Sub-Order 1. Hydrocorallia, Hydroid stocks, with calcined peri- Vanting. derm skeleton. The sexual products areproduced in gonophores. Stylasti r, 68 COMPARATIVE ANATOMY CHAP. Hydroid form. Sub-Order 2.Tubularia. Small hydroid colonies, naked orcovered with a chitinous envelope (peri-derm). The chitinous envelope neverwidens into a cup (theca) round the polyphead. In man

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