. A text-book of invertebrate morphology. Invertebrates. 104 INVERTEBRATE MORPHOLOGY. EpHyra seems to represent an ancestral stage, since some mature medusae resemble this stage very closely and it occurs in the life-history of all, and earlier than this is the Scyphostoma representing the Lucernaria stage of evolution. The Scyphostoma has superficial resemblance to a hydroid. FiQ. -A, Scyphostom of Aurelia; B, Strobila of Aurelia; C, Ephyra of Pelagia (all after Agassiz). polyp, which resemblance is almost an identity in the earlier stages of the Scyphostoma before the development of the
. A text-book of invertebrate morphology. Invertebrates. 104 INVERTEBRATE MORPHOLOGY. EpHyra seems to represent an ancestral stage, since some mature medusae resemble this stage very closely and it occurs in the life-history of all, and earlier than this is the Scyphostoma representing the Lucernaria stage of evolution. The Scyphostoma has superficial resemblance to a hydroid. FiQ. -A, Scyphostom of Aurelia; B, Strobila of Aurelia; C, Ephyra of Pelagia (all after Agassiz). polyp, which resemblance is almost an identity in the earlier stages of the Scyphostoma before the development of the mesenteries and funnels. This suggests a relationship of the Scyphomedusas to the Hydromedusaa only through the polyp, the separation of the two classes having occurred be- fore the appearance of the medussB on the scene. III. Class Anthozoa. The Anthozoa never assiime the medusa form, but are ses- sile, usually colony-producing polyps of the Scyphostoma type. Typically they are cylindrical structures (Fig. 56) at- tached at one extremity, the hase, and bearing at the other extremity the mouth in the centre of a flat surface, the disk, around the margins of which are a number of hollow tenta- cles. The coelenteron is imperfectly divided into a number of chambers by longitudinal partitions arising from the body- wall, the mesenteries (Fig. 57, me), the various intermesenterial. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original McMurrich, J. Playfair (James Playfair), 1859-1939. New York, H. Holt and Company
Size: 1434px × 1742px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
