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Echinosigra phiale (ontogeny of apical system)
Description Development of the apical system during ontogeny. a. The plates from a continuous, compact disc, the anterior genital plate having only a single hydropore. b. The anterior genital plate begins to differentiate into two plates, G2 and G3. c. With the opening of the gonopores G3 forms a distinct plate with a second gonopore. d. The posterior part of the apical system, G1 and G4, plus ocular plates OI and OV, shifted to the posterior. The anterior part, containing ocular plate OIII, the two perforated anterior genital plates G2 and G3, and the two ocular plates OII and OIV is now separated from the posterior part. This posterior part being continuous distinguishes Echinosigra from Pourtalesia, where the posterior genital plates G1 and G4 are disrupted also from the posterior oculars OI and OV.
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added on 2009-02-23638 viewsFrom reference Schultz, H. (2009). Sea urchins II: Worldwide irregular d...
© 2009 Schultz, Heinke
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