Sentence Examples with the word Hydrotheca

The gymnoblastic polyp usually has a distinct perisarc investing the hydrorhiza and the hydrocaulus, sometimes also the hydranth as far as the bases of the tentacles (Bimeria); but in such cases the perisarc forms a closely-fitting investment or cuticule on the hydranth, never a hydrotheca standing off from it, as in the next sub-order.

The characteristic hydrotheca is formed by the bud at an early stage (fig.

I, The horny cup or hydrotheca of the hydriform persons; 1, medusiform person springing from m, a modified hydriform person (blastostyle); n, the horny case or gonangium enclosing the blastostyle and its buds.

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An important variation is seen, in the form of the hydrotheca itself, which may come off from the main stem by a stalk, as in Obelia, or may be sessile, without a stalk, as in Sertularia.

This and the hydrotheca i give origin to the name Calyptoblastea.

Hydrocaulus, and forms a cup, the hydrangium or hydrotheca (h, t), standing off from the body, into which the hydranth can be retracted for shelter and protection.

A-D are stages common to both; from D arises the hydrotheca (E) or the gonotheca (F); th, theca; st, stomach; 1, tentacles; m, mouth; mb, medusa-buds.