The edges of the mantle are united posteriorly except at the anal and branchial apertures, which are placed at the ends of two very short siphons or tubular prolongations of the mantle; the siphons bear a number of short tentacles, and many of these are furnished with eye-spots.
They are bulbous plants, the slender stems of which support themselves by tendril-like prolongations of the tips of some of the narrow generally lanceolate leaves.
They are shrubby plants climbing over surrounding vegetation by means of tendrillike prolongations of the midrib of the leaf beyond the leaf-tip.
The gonads are paired and hermaphrodite, they form a pair of anterior prolongations of the pericardium, extending nearly to the anterior end of the body.
Sometimes the prolongations of these wires are carried horizontally or dipped down so as to form an umbrella antenna (fig.
The tentaculocysts are implanted round the margins of the lobes of the umbrella and may be supported by prolongations of the ectodermal rim termed otoporpae (Gehorspangen).
Many of the Aegean islands, or chains of islands, are actually prolongations of promontories of the mainland.
They are often horizontal, as in Cathartocarpus Fistula, where they consist of transverse cellular prolongations from the walls of the ovary, only developed after fertilization, and therefore more properly noticed under fruit.