The genus Trigonocyclia (only known by one single species, once observed) bears on the margin of the chambered disk three solid radial spines, at equal distances one from another. It corresponds to the genus Tripodictya amongst the Porodiscida.
1. Trigonocyclia triangularis, n. sp. (Pl. [37], fig. 5).
Phacoid shell three times as broad as the medullary shell, connected with it by six equidistant radial beams, three of which are prolonged into marginal spines. In the equatorial plane only one single chambered ring, divided by forty-four radial beams into narrow chambers. Pores large, irregular, roundish; five on the radius of the phacoid shell, two on each chamber. Surface and margin of the disk spiny. Three strong conical marginal spines, divergent at equal angles, as long as the radius of the disk.
Dimensions.—Diameter of the disk 0.16, of the phacoid shell 0.12, of the medullary shell 0.04.
Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms, Pullen.
Genus 201. Staurocyclia,[[240]] Haeckel, 1881, Prodromus, p. 458.
Definition.—Coccodiscida with four solid radial spines on the margin of the disk, crossed in two equatorial diameters perpendicular one to another. Medullary shell simple.
The genus Staurocyclia is characterised by four radial spines on the margin of the disk, which are opposite in pairs and situated in two equatorial diameters, commonly perpendicular one to another. They form therefore a rectangular cross (rarely more or less irregular). The genus corresponds exactly to Staurodictya in the family Porodiscida. The medullary shell is simple.
1. Staurocyclia cruciata, n. sp. (Pl. [37], fig. 1).
Phacoid shell two and a half times as broad as the medullary shell, surrounded by six to eight regular rings, which are divided by fifty to seventy piercing beams into square chambers. Pores regular, circular; six on the radius of the phacoid shell, one single pore on each chamber. Four crossed radial spines, arising from the medullary shell by thin bases, prolonged over the dentated margin as four strong quadrangular swords, as long as the radius of the disk.