5. Stylochlamydium perispirale, Haeckel.
Perichlamydium limbatum, var. Stöhr, 1880, Palæontogr., vol. xxvi. p. 109, Taf. v. fig. 1.
Inner rings of the disk concentric, circular, outer rings convoluted spirally, all rings of equal breadth. Pores regular, circular, two on the breadth of each ring, twice as large as in the equatorial girdle, which is about half as broad as the radius of the disk. Twelve to sixteen bristle-shaped radial spines, irregularly disposed, are connected by the girdle near to the points.
Dimensions.—Diameter of the disk (with six rings) 0.12, with the girdle 0.2; breadth of each ring 0.011; pores in the central disk 0.004, in the girdle 0.002.
Habitat.—Fossil in Tertiary rocks of Sicily, Grotte, Stöhr.
6. Stylochlamydium spongiosum, Haeckel.
Perichlamydium spongiosum, Stöhr, 1880, Palæontogr., vol. xxvi, p. 109, Taf. v. fig. 3.
Rings of the disk partly concentric, partly spiral, more or less irregular and often interrupted, with increasing breadth from the centre. Central part of the disk more or less spongy and obscure. Equatorial girdle half as broad as the radius of the chambered disk, with smaller pores than the latter, pierced by twenty to thirty thin, bristle-shaped radial beams, which proceed over the margin of the disk.
Dimensions.—Diameter of the disk (with ten rings) 0.2, with the girdle 0.3; breadth of the rings 0.005 to 0.015; pores 0.001 to 0.005.
Habitat.—Pacific, central area, Station 268, depth 2900 fathoms; also fossil in the Tertiary rocks of Barbados and Sicily.