Lampoxanthium brevispiculum, Haeckel, 1882, Atlas.
Spicula short and thick, thorny, irregularly curved, pointed at both ends, very numerous. In the observed specimen all spicula were aggregated in the outer part of the voluminous calymma, whilst the inner alveolated part was devoid of them. Central capsule thick walled, with a layer of large oil-globules on its inner surface, twice as broad as the large nucleus which contains numerous nucleoli.
Dimensions.—Diameter of the central capsule 0.5, of the nucleus 0.2, of the calymma 2.5.
Habitat.—South Atlantic, Station 334, surface.
Genus 11. Lampoxanthium,[[20]] n. gen.
Definition.—Thalassosphærida with numerous large alveoles in the calymma (but not in the central capsule), and with numerous branched or compound spicula in the calymma.
The genus Lampoxanthium differs from the foregoing, Thalassoplancta, by the composite form of the spicula, which are not simple needles, but radiate or geminate, or branched in different forms; the former stands therefore in the same relation to the latter as the social Belonozoum to Sphærozoum. The spicula of some species of Lampoxanthium are identical with those of some species of Sphærozoum, so that the latter may be derived from the former by forming colonies. The large central capsule is enveloped by a very voluminous alveolated calymma, and includes a large central nucleus with numerous nucleoli.
Subgenus 1. Lampoxanthella, Haeckel.
Definition.—Spicula all (or nearly all) of one kind, radiate.
1. Lampoxanthium tetractinium, n. sp.