Definition.—Phæodinida with three apertures to the central capsule (an astropyle on the oral pole of the main axis, and two lateral parapylæ on both sides of the aboral pole).
The genus Phæodina has the same structure of the central capsule as the majority of Phæodaria; one large main-opening or astropyle on the oral pole of the main axis, and two smaller lateral accessory openings or parapylæ on each side of the aboral pole: it is therefore a true Tripylean genus, like the majority of Phæodaria.
1. Phæodina tripylea, Haeckel (Pl. [101], fig. 2).
? Tripylea sp., R. Hertwig, 1879, Organismus d. Radiol., Taf. x. figs. 1, 11.
Central capsule spheroidal or lenticular, somewhat depressed in the direction of the main axis. Astropyle with a strongly ribbed, radiate operculum, scarcely one-third as broad as the diameter of the capsule, and prolonged into a short tubular proboscis. Parapylæ also with short tubular openings. The outer strong (double-contoured) membrane of the central capsule is separated from the inner thin (simple-contoured) membrane by a wide interval, filled up by a clear fluid or jelly; only at the three apertures both membranes are in direct connection. The granulated protoplasm contains numerous vacuoles, and surrounds a large spheroidal nucleus, with numerous small nucleoli. The voluminous calymma in a specimen, observed living, was alveolar, and the ramification of the pseudopodia, as well as the formation of the dark brown phæodium, very similar to that of Dictyocha stapedia (Pl. [101], fig. 10). Another specimen, figured in Pl. [101], fig. 2, exhibited the first stages of self-division; the reticulated nucleus and the radiate operculum of the astropyle were already doubled, and the two membranes of the capsule between them constricted in the median plane. To this species belong probably the central capsules figured by R. Hertwig, loc. cit.
Dimensions.—Diameter of the central capsule 0.15 to 0.25, of the nucleus 0.06 to 0.1, of the calymma 0.8 to 1.2.
Habitat.—Mediterranean; Portofino, near Genoa (Haeckel); Messina (Hertwig).
2. Phæodina cannopylea, n. sp.
Central capsule subspherical, scarcely depressed in the direction of the main axis. Astropyle with a finely ribbed radiate operculum, about as broad as the radius of the capsule, prolonged into a slender, tubular proboscis which is S-shaped, about as long as the radius, and similar to that of Phæocolla primordialis, Pl. [101], fig. 1. Parapylæ also tubular, with two slender prolongations, half as long and broad as the proboscis of the parapyle. Nucleus spheroidal, about half as broad as the capsule. This species differs from the preceding mainly in the cylindrical slender prolongations of the three apertures, which are similar to those of Aulosphæra and Aularia (Pl. [111], fig. 2).
Dimensions.—Diameter of the central capsule 0.2, of the nucleus 0.1, of the calymma 1.2 to 1.5.