Family XXXI. Phorticida, Haeckel (Pl. , figs. 10, 11)

Phorticida, Haeckel, 1881, Prodromus, p. 464.

Definition.—Larcoidea with quite irregular monothalamous shell, representing irregular modifications of an original lentelliptical latticed shell; the irregular cortical shell encloses a regular or subregular, lentelliptical or trizonal medullary shell.

The family Phorticida comprises a small number of Larcoidea in which a subregular, trizonal, lentelliptical medullary shell is enclosed by an irregular simple or spongy cortical shell. The lattice-work of the latter is sometimes simple and complete, at other times incomplete, with open gates (as in the Pylonida), sometimes also spongy. Its form is always more or less irregular, roundish, often dimply or tuberous; different from most other Larcoidea.

The medullary shell is constantly a regular or subregular Larnacilla-shell, composed of three elliptical latticed girdles of different sizes, perpendicular one to another. This leaves no doubt that the Phorticida are true Larcoidea. The connection of it with the cortical shell is rarely effected by radial beams, commonly by two opposite latticed wings, which are identical with the lateral halves of the transverse girdle in the Pylonida diplozonaria (Amphipyle, Tetrapyle). Often also between this transverse and a second (lateral) girdle there remain large open gates, so that the affinity between these Phorticida and the Pylonida cannot be doubted. In other cases these gates become closed, so that they more nearly approach the Larnacida. From both families they differ by the irregularity of the papillate or tuberous cortical shell. The network is more or less irregular, its surface often thorny, but never covered with symmetrically disposed radial spines.

The central capsule is lentelliptical, encloses the medullary shell, and is enveloped by the cortical shell, as in the nearly allied Pylonida and Larnacida, of which the Phorticida may be regarded as irregular aberrant forms.

Synopsis of the Genera of Phorticida.

Cortical shell simply latticed, 313. Phorticium.

Cortical shell spongy, 314. Spongophortis.

Genus 313. Phorticium, Haeckel, 1881, Prodromus, p. 464.

Definition.—Phorticida with irregular cortical shell of simple lattice-work, enclosing a lentelliptical Larnacilla-shaped medullary shell.

The genus Phorticium comprises all Phorticida in which the irregular cortical shell is formed by simple lattice-work, not by spongy framework. We can divide this genus into two subgenera: in Phortopyle (as in the Pylonida) the lattice-work of the cortical shell exhibits large openings or gates; in Phortolarcus these gates are perfectly closed by network; the former may be regarded as abnormal or irregular Pylonida, the latter as modifications of Larnacida.

Subgenus 1. Phortopyle, Haeckel.

Definition.—Lattice-work of the irregular cortical shell incomplete, with large openings or gates.

1. Phorticium pylonium, n. sp. (Pl. , fig. 10).

Cortical shell irregular, roundish, about three times as large as the enclosed lentelliptical, regular, Larnacilla-shell, connected with it by some radial beams and irregularly latticed girdles; between these remain four to eight large open gates of irregular roundish form and size; and these gates are the same as in Tetrapyle and Octopyle. This very variable species may be regarded as a monstrosity of those genera of Pylonida; it is very common, but all individuals are more or less unequal; some specimens approach to some common species of Tetrapyle. The surface of the shell is more or less spiny.

Dimensions.—Diameter of the irregular cortical shell 0.12 to 0.18; length of the lentelliptical medullary shell 0.05 to 0.06, breadth 0.035 to 0.045.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, &c., common, surface and in various depths.

2. Phorticium spironium, n. sp.

Cortical shell irregular, roundish, tuberous, about four times as large as the enclosed subregular Larnacilla-shell, connected with it by some irregular radial beams, and by opposite, spirally begining, irregularly latticed girdles, comparable to those of Spironium; between them remain six to twelve large open gates of irregular size and form. Surface rough. The resemblance to some forms of Spironium makes it probable that this species is a deformity or monstrosity of that genus.

Dimensions.—Diameter of the irregular cortical shell 0.12 to 0.2, of the lentelliptical medullary shell 0.03 to 0.06.

Habitat.—Pacific, central area, Stations 270 to 274, surface, and in various depths.

Subgenus 2. Phortolarcus, Haeckel.

Definition.—Lattice-work of the irregular cortical shell complete, without large openings or gates.

3. Phorticium deforme, n. sp.

Cortical shell irregular, roundish or longish, three times as large as the enclosed subregular, lentelliptical Larnacilla-shell, connected with it by two opposite latticed wings (the halves of the transverse girdle of Tetrapyle). Network of the cortical shell irregular, dense, perfectly closed, without larger openings or gates. Surface thorny. (May be regarded as a monstrous form of Larnacalpis.)

Dimensions.—Diameter of the irregular cortical shell 0.15 to 0.18, of the medullary shell 0.04 to 0.06.

Habitat.—Pacific, central area, Station 272, depth 2600 fathoms.

4. Phorticium abnorme, n. sp.

Cortical shell irregular, roundish, tuberous, with five to ten quite irregular or nearly hemispherical protuberances, which resemble the cupolas of Zonarida. The regular lentelliptical Larnacilla-shell is one-third to one-fourth as large as the enclosing cortical shell, and is connected with it by some irregular radial beams. Lattice-work completely closed, without gates. Surface spiny. (May be regarded as an anomalous form of Zonidium; as in the other species of this variable genus, the individuals are very unequal.)

Dimensions.—Diameter of the irregular cortical shell 0.12 to 0.2, of the medullary shell 0.03 to 0.05.

Habitat.—Atlantic and Pacific, tropical zone, surface, and at various depths.

Genus 314. Spongophortis, Haeckel, 1881, Prodromus, p. 464.

Definition.—Phorticida with irregular cortical shell of spongy framework, enclosing a lentelliptical Larnacilla-shaped medullary shell.

The genus Spongophortis differs from Phorticium in the spongy framework of the cortical shell. This encloses the inner Larnacilla-shaped medullary shell either directly, or both shells are separated by a hollow interval, and connected either by radial beams or by latticed lamellæ. Perhaps both these subgenera might be better separated as genera.

Subgenus 1. Stypophorticium, Haeckel.

Definition.—Spongy cortical shell immediately enclosing the lentelliptical medullary shell, without hollow interval.

1. Spongophortis spongiosa, n. sp.

Cortical shell irregular, roundish, rough or tuberous, composed of loose spongy framework, which immediately envelops the lentelliptical central Larnacilla-shell; the diameter of the former becomes about five to six times as large as that of the latter.

Dimensions.—Diameter of the spongy cortical shell 0.15 to 0.25, of the trizonal medullary shell 0.03 to 0.04.

Habitat.—Pacific, central area, Station 274, surface.

Subgenus 2. Spongophorticium, Haeckel.

Definition.—Spongy cortical shell separated by a hollow interval from the lentelliptical medullary shell.

2. Spongophortis radiosa, n. sp.

Cortical shell irregular, roundish, four to five times as large as the enclosed lentelliptical Larnacilla-shell, with which it is connected by ten to twenty irregularly disposed radial beams. Spongy framework compact, about as thick as the medullary shell. Surface covered with numerous short, bristle-shaped, radial spines.

Dimensions.—Diameter of the spongy cortical shell 0.15 to 0.2, of the trizonal medullary shell 0.035 to 0.045.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

3. Spongophortis larnacilla, n. sp. (Pl. , figs. 11a-11d).

Cortical shell irregular, roundish, tuberous, three to four times as large as the enclosed lentelliptical Larnacilla-shell, connected with it by two opposite latticed wings (the halves of the transverse girdle of Tetrapyle). Spongy framework compact, about half as thick as the medullary shell. Surface rough. (May be regarded as an abnormal Tetrapyle or Larnacalpis, with an irregular spongy cortical shell.)

Dimensions.—Diameter of the spongy cortical shell 0.16 to 0.2, of the trizonal medullary shell 0.04 to 0.06.

Habitat.—Pacific, central area, Station 271, depth 2425 fathoms.