Synopsis of the Genera of Phæodinida.
| Central capsule with a single opening (an astropyle on the oral pole), | 656. Phæocolla. |
| Central capsule with three openings (an oral astropyle and two aboral parapylæ), | 657. Phæodina. |
Genus 656. Phæocolla,[[274]] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 4.
Definition.—Phæodinida with a single aperture to the central capsule (an astropyle with radiate operculum, placed on the oral pole of the main axis).
The genus Phæocolla may be regarded as the simplest form of all Phæodaria, and perhaps as the common ancestral form of this legion. It has no skeleton, and the central capsule exhibits only a single aperture on one pole of the main axis. In this it agrees with the Challengerida, Medusettida, and Castanellida, which have also no parapylæ or secondary openings.
1. Phæocolla primordialis, n. sp. (Pl. [101], fig. 1).
Central capsule subspherical, or somewhat depressed in the direction of the main axis. The oral pole of the latter exhibits a large astropyle, or a radiate operculum, about as broad as the nucleus. From its centre arises a conical mammilla, prolonged into a thin, cylindrical, S-like tubulus, the proboscis, which is about as long as the diameter of the capsule. The outer membrane of the capsule is thick and double-contoured; the inner is very thin, but distinct, and includes finely granulated protoplasm, and numerous spherical, clear vacuoles, each with some small granules. Nucleus spheroidal, depressed in the direction of the main axis, containing numerous dark, irregularly amœbiform nucleoli. The diameter of the nucleus is about equal to the radius of the central capsule. The extracapsular calymma is an alveolated sphere, the diameter of which is six to eight times that of the capsule. The inner part of it contains an irregular, blackish phæodium, which surrounds and hides the oral half of the central capsule.
Dimensions.—Diameter of the central capsule 0.16, of the nucleus 0.08, of the calymma 1.0 to 1.2.
Habitat.—Central Pacific, Station 271 to 274, surface.