Dimensions.—Diameter of the shell 0.55, of the pores 0.012 to 0.016.
Habitat.—North Atlantic, Station 354, surface.
Genus 710. Castanura,[[327]] Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, Dec. 12, p. 5.
Definition.—Castanellida with branched radial main-spines and a dentate mouth.
The genus Castanura differs from the preceding Castanopsis in the possession of a corona of teeth surrounding the mouth, similar to that of Castanissa. It differs from the latter in the ramification of the radial main-spines, wherein it agrees with the former. Castanura may therefore be derived either from Castanissa by ramification of the main-spines, or from Castanopsis by development of teeth around the mouth.
1. Castanura tizardi, n. sp. (Pl. [113], fig. 4, 4a).
Pores regular, circular, without hexagonal frames, twice as broad as the bars. Bristles twice as long as one pore. Radial main-spines somewhat longer than the radius, straight, very stout, with irregular lateral branches, which are partly confluent. Mouth with six strong conical teeth.
Dimensions.—Diameter of the shell 0.6, of the pores 0.03.
Habitat.—Tropical Atlantic, Station 346, surface.
2. Castanura havergali, n. sp.