Outlines of zoology . Fig. 81.—Z, Diagrammatic section of Zoantharian ; A, ofAlcyonarian.—^After Chun. The line 5^ in Z is through the siphonoglyphes (a), the lineT-T passes through two inter-septal spaces. The retractormuscles are represented by dark thickenings on the mesen-teries—all on one (the ventral) side in the Alcyonarian. Theline .S*-^ in A represents the axis of symmetry. some cases the ovum segments into a solid morula; this becomes afree planula, in which a cylindrical depression at one pole formsthe mouth and gullet. Or the two layers may be established bya process known as delam
Outlines of zoology . Fig. 81.—Z, Diagrammatic section of Zoantharian ; A, ofAlcyonarian.—^After Chun. The line 5^ in Z is through the siphonoglyphes (a), the lineT-T passes through two inter-septal spaces. The retractormuscles are represented by dark thickenings on the mesen-teries—all on one (the ventral) side in the Alcyonarian. Theline .S*-^ in A represents the axis of symmetry. some cases the ovum segments into a solid morula; this becomes afree planula, in which a cylindrical depression at one pole formsthe mouth and gullet. Or the two layers may be established bya process known as delamination, in which a single layer of cells isdivided into an inner endodermic and an outer ectodermic to Goette, the development is in essentials the same as thatof the Hydra-tuba. The larva of Cerianthids is for a time pelagic, andused to be recognised as a distinct genus, Arachnactis. Related forms. —The sea-anemones are classified in the sub-classAnthozoa or Actinozoa, and along with many cor
Size: 1397px × 1789px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192, booksubjectzoology
