7. Eucoronis challengeri, n. sp. (Pl. [82], fig. 4).
Lithocoronis challengeri, Haeckel, 1881, Prodromus, p. 445.
Frontal ring violin-shaped, one and a half times as broad as high, with a strong sagittal constriction. Sagittal ring nearly circular, two-thirds as high as the frontal ring. Both rings armed with numerous irregularly branched spines. (The specimen figured, with red central capsule and numerous xanthellæ, was observed living by me at the Canary Islands.)
Dimensions.—Height of the frontal ring 0.1 to 0.12, breadth 0.14 to 0.17.
Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, surface and at various depths.
Genus 419. Plectocoronis,[[38]] Haeckel, 1881, Prodromus, p. 445.
Definition.—Coronida with six large, partly latticed gates (four lateral and two basal). Skeleton composed of two complete rings (the sagittal and basal) and one incomplete (frontal) ring. Basal ring without developed typical feet.
The genus Plectocoronis differs from the preceding Eucoronis, its ancestral form, in the development of loose irregular lattice-work along the two meridional rings, and therefore bears to it the same relation that Acanthodesmia does to Coronidium. If the lattice-work become more complete and close the gates, these Coronida pass over directly into Spyroidea (Zygospyrida).
1. Plectocoronis anacantha, n. sp.
Basal ring and frontal ring elliptical, without sagittal constriction. Sagittal ring ovate. The frontal and sagittal rings are bordered on both edges with an incomplete series of small irregular pores. All three rings smooth, without spines.