Page:Scientific results HMS Challenger vol 18 part 2.djvu/436

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Definition.— (vel Dicyrtida eradiata clausa) with a free cephalis, without apical horn.

The genus Dicolocapsa differs from the preceding Sethocapsa in the loss of the apical horn, and therefore bears to it the same relation that Dictyocephalus does to Sethocyrtis.

1. Dicolocapsa microcephala, n. sp. (Pl. 57, fig. 1).

Shell smooth, thin-walled, with distinct collar stricture. Cephalis small, subspherical, with small, crowded pores. Length of the two joints = 1 : 3, breadth = 1 : 3. Thorax also nearly spherical, three times as large as the cephalis, with small, irregularly scattered, circular pores, and much broader bars.

Dimensions.—Cephalis 0.03 diameter, thorax 0.09 diameter.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Dicolocapsa megacephala, n. sp.

Shell smooth, thin-walled, with sharp collar stricture. Cephalis large, conical, obtuse. Length of the two joints = 5 : 9, breadth = 6 : 8. Thorax ovate, truncate, with hemispherical base. Pores of both joints equal, subregular, circular, about as broad as the bars.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Dicolocapsa platycephala, n. sp.

Shell papillate, thick-walled, with slight collar stricture. Cephalis flat, hemispherical, hyaline, without pores (or with few small pores). Length of the two joints = 2 : 11, breadth = 4 : 9. Thorax ovate, with small, regular, circular pores, half as broad as the bars.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.11 long, 0.09 broad.

Habitat.—Fossil in Barbados.

Definition.— (vel Dicyrtida eradiata clausa) with a cephalis hidden in the thorax, without apical horn.