Page:Scientific results HMS Challenger vol 18 part 2.djvu/883

Rh

Definition.— with an odd sagittal frenulum on each galea and an outer lattice-mantle, armed with sixteen styles (two odd and six paired styles on each valve).

The genus Cœlagalma represents the highest degree of development among the Cœlographida, and exhibits the maximum number of coronal styles in this family, viz., sixteen (eight on each valve). Two of these are odd (as in Cœlospathis and Cœlostylus), viz., the longitudinal anterior nasal style, and the horizontal sagittal style. The six others are paired (as in Cœloplegma), viz., two anterior or pectoral, two lateral or frontal, and two posterior or tergal styles. Since Cœlagalma in this highest developed armature exceeds all the other Cœloplegmida, and exhibits at the same time the utmost complexity in structural detail, it may be regarded as one of the most perfect forms not among the only, but among all Radiolaria.

1. Cœlagalma mirabile, n. sp. (Pl. 126, figs. 4, 4a).

Shell-mantle one and a half times as long as broad, its frontal perimeter (fig. 4a) heptagonal, with seven concave sides, its sagittal perimeter octagonal, its equatorial perimeter hexagonal (fig. 4b), the corners of the polygons are marked by the sixteen prominent styles. Nasal odd style longer; and sagittal odd style shorter, than the six paired styles of each valve; the two pectoral styles are directed forwards, the two lateral styles are nearly opposed in the horizontal frontal diameter, while the two shorter tergal styles are directed backwards. The terminal coronets (at the distal ends of the sixteen styles) are four times forked, with sixteen equal spinulate fingers, each finger at the distal end with eight recurved teeth. The entire surface of the bivalved latticed mantle is densely studded with hundreds of most elegant anchor-pencils, so that the external appearance of this beautiful species becomes one of the most wonderful among Radiolaria.

Dimensions.—Length of the shell 5.4, breadth 3.6.

Habitat.—Central area of the Pacific, Station 271, depth 2425 fathoms.