Sub-Fam. 2. Cymbonectinae.—The primary nectocalyx is thrown off, and is replaced by a secondary and permanent nectocalyx—Cymbonectes, Muggiaea, and Doramasia.
Fam. 2. Diphyidae.—The primary mitre-shaped nectocalyx is thrown off and replaced by two secondary rounded, prismatic, or pyramidal, heteromorphic nectocalyces.
This family contains several sub-families, which are arranged in two groups: the Diphyidae Oppositae, in which the two secondary bells are opposite one another, and do not exhibit pronounced ridges; and the Diphyidae Superpositae, in which one of the two secondary nectocalyces is situated in front of the other, and each nectocalyx is provided externally with very definite and often wing-like ridges. In all the Diphyidae Oppositae the cormidia remain attached, whereas in most of the Diphyidae Superpositae they become free-swimming, as in the Monophyidae.
The sub-families of the Diphyidae Oppositae are:—
Sub-Fam. 1. Amphicaryoninae.—One of the two secondary nectocalyces becomes flattened above to form a shield, and at the same time its sub-umbrellar cavity is atrophied, and its radial canals reduced. Mitrophyes, Atlantic Ocean.
Sub-Fam. 2. Prayinae.—The colony exhibits a pair of large, obtuse nectocalyces, with a relatively small sub-umbrellar cavity. Praya, Mediterranean and Atlantic.
Sub-Fam. 3. Desmophyinae.—The colony bears a large number of reserve or tertiary nectocalyces arranged in two rows. Desmophyes, Indian Ocean.
Sub-Fam. 4. Stephanophyinae.—There are four nectocalyces arranged in a horizontal plane. Each one of the cormidia bears a nectocalyx, which is periodically replaced. This sub-family is constituted for Stephanophyes superba from the Canary Islands. It attains a length of 25 cm., and is probably the largest and most beautiful of all the Calycophoridae.[[339]]
The group Diphyidae Superpositae contains the following:—
Sub-Fam. 1. Galeolarinae.—Galeolaria.