Nassellaria

Definition and stakes

Portrait of Ernst Haeckel Ernst Haeckel Report on the Radiolaria Collected by H.M.S. Challenger During the Years 1873-1876…

The Skeleton of the Nassellaria.—The skeletons of the Nassellaria or Monopylea consist of silica, and are never composed of separate portions, but constitute always a single continuous piece. The ground-form is originally monaxon, corresponding to that of the central capsule, with a constant difference between the two poles of the vertical main axis. The ground-form is never spherical or polyaxon as in the lattice-shells of the Spumellaria, and the skeleton never consists of hollow tubes, as in the Phæodaria. The legion Nassellaria may be divided into two orders
Source: Gutenberg

Portrait of Ernst Haeckel Ernst Haeckel Report on the Radiolaria (1887)

Definition.—Nassellaria with a rudimentary, originally tripodal skeleton, composed of radial spines, arising from one common central point or central rod; the spines are simple or branched, and the branches may form by concrescence of their meeting ends a loose wickerwork, but never a complete lattice-shell. Never a ring in the skeleton.
The suborder Plectoidea, hitherto known by few species only of "Plagiacanthida," comprises a large number of interesting Nasselaria, which belong partly to the simplest and most primitive forms of this legion.
Source: Wikisource

Portrait of Ernst Haeckel Ernst Haeckel Report on the Radiolaria (1887)

The family Nassellida comprises the simplest and most primitive forms of Nassellaria, the only group which is entirely without a skeleton. The central capsule is therefore perfectly free and naked, enveloped by the calymma only, as in the Colloidea among the Spumellaria, in the Phæodinida among the Phæodaria. Probably these naked and skeletonless Monopylea must be regarded as surviving remnants of the common ancestral group of this legion
Source: Wikisource

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