. The Danish Ingolf-expedition. ph c om freigelegt wird (p. 652) is a confirmation of the homology between this vessel and the excretoryvessel of Ctenophores. Anything corresponding to the other excretory vessel of Ctenophores is notfound in the grown Polyclads, (where it would have to be sought for below the brain) but Langhas found an indication of it in the early stages of development. The two accompanying diagrams,copied from Lang show these features clearly. The main axis given, the other plans are easily found. The excretory vessels lying y s^gX—^ ^ always in the sagittal plane, it
. The Danish Ingolf-expedition. ph c om freigelegt wird (p. 652) is a confirmation of the homology between this vessel and the excretoryvessel of Ctenophores. Anything corresponding to the other excretory vessel of Ctenophores is notfound in the grown Polyclads, (where it would have to be sought for below the brain) but Langhas found an indication of it in the early stages of development. The two accompanying diagrams,copied from Lang show these features clearly. The main axis given, the other plans are easily found. The excretory vessels lying y s^gX—^ ^ always in the sagittal plane, it is accord-ingly the longitudinal axis of the Polycladswhich corresponds to the sagittal axis ofCtenophores, the transverse axis of thelatter being then also transverse in Poly-clads. From this then naturally followsthat the nuchal tentacles of some primitivePolyclads (Planoceridae) are regarded ashomologues of the tentacles of Ctenophores,being placed in the transverse plan. The gastrovascular system of Poly-clads and Ctenoph
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Keywords: ., bookcentury1800, bookdecade1890, booksu, booksubjectmarineanimals
