Page:Scientific results HMS Challenger vol 18 part 1.djvu/1034

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Definition.—Plates of the shell smooth, without crests, not dimply.

1. Coscinaspis peripora, n. sp. (Pl. 138, fig. 1).

Shell thin walled, with smooth surface, without crests and dimples, perforated by pores of very different sizes. Forty aspinal pores, roundish or elliptical, of about the same size as the fifty or sixty violin-shaped sutural pores, and three to four times as broad as the small roundish coronal pores, which are irregularly formed and distributed, four to eight occurring on each plate (altogether one hundred to one hundred and twenty). Radial spines roundish, somewhat compressed; inner and outer half nearly of the same length.

Dimensions.—Diameter of the shell 0.12, aspinal pores 0.01 to 0.012, coronal pores 0.003.

Habitat.—North-West Pacific, Station 235, surface.

2. Coscinaspis stigmopora, n. sp.

Shell very thin walled, with smooth surface, without crests and dimples, perforated by pores of very different sizes. Forty aspinal pores, roundish, of about the same size as the fifty or sixty violin-shaped sutural pores, their diameter being about one-fifth of that of the plates. Coronal pores very numerous (two hundred to four hundred) and very small, irregularly scattered, ten to twenty occurring in each plate. Sutures strongly denticulated. Radial spines very thin and short, cylindrical.

Dimensions.—Diameter of the shell 0.12 to 0.15, aspinal and sutural pores 0.01, coronal pores 0.001 to 0.003.

Habitat.—North Pacific, Station 257, surface.

3. Coscinaspis rhacopora, n. sp.

Shell very thin walled, with smooth surface, without crests and dimples, perforated by very irregular pores of very different sizes and forms; commonly more or less lobed or sinuate. Forty aspinal pores and fifty to eighty sutural pores, larger than the numerous (one hundred to two hundred) irregularly scattered coronal pores. Sutures very sinuate. Radial spines cylindrical, thin and long.

Dimensions.—Diameter of the shell 0.15 to 0.18, aspinal and sutural pores 0.01 to 0.02, coronal pores 0.001 to 0.005.

Habitat.—Central Pacific, Station 274.

4. Coscinaspis coscinopora, n. sp.

Shell thin walled, with smooth surface, without crests and dimples, perforated by very numerous pores of circular form, but of different sizes. Forty aspinal pores and one hundred to two hundred