Order 2. Coenothecalia.
Order 3. Alcyonacea.
Order 4. Gorgonacea.
Order 5. Pennatulacea.
Grade A. Protoalcyonacea.
This Grade includes those genera which, like many sea-anemones, do not reproduce by continuous gemmation to form colonies.
Several genera have been described, and they have been placed together in one family called the Haimeidae.
Haimea funebris, M. Edwards, was found off the coast of Algeria; H. hyalina, Koren and Danielssen, in Norway; Hartea elegans, Wright, from the Irish coast; Monoxenia darwinii, Haeckel, from the Red Sea, and a large new species found by the "Siboga" Expedition in deep water off Ceram. All these species, however, are very rare, and there is no satisfactory evidence at present that they remain solitary throughout life.
Grade B. Synalcyonacea.
The sub-division of the Synalcyonacea into orders presents many difficulties, and several different classifications have been proposed. Only two orders of the five that are here recognised are clearly defined, namely, the Coenothecalia, containing the single living genus Heliopora, and the Pennatulacea or Sea-pens; the others are connected by so many genera of intermediate characters that the determination of their limits is a matter of no little difficulty.