Page:Scientific results HMS Challenger vol 18 part 2.djvu/876

1752 long divergent styles arise from each tergal tube. The hindermost of these is the longest, three times as long as the diameter of the fork-thicket. All anchor-pencils have nearly equal size.

Dimensions.—Diameter of the whole body 22, of the fork-thicket 5.2.

Habitat.—South Pacific, Station 166 (west of New Zealand), depth 275 fathoms.

4. Cœlothamnus maximus, n. sp.

Sixteen styles straight, of different sizes. The four frontal main tubes are already forked at the base, so that from each frontal corner of the two galeæ two divergent tubes, an anterior or pectoral and a posterior or tergal, arise. Each of these is again forked, and each branch prolonged into a very long verticillate style. The hindermost style of each side is the longest, twice as long as the foremost, and one and a half times as long as the two intermediate styles. The size of the anchor-pencils decreases in the distal third of the styles.

Dimensions.—Diameter of the whole body 32, of the fork-thicket 7.5.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Definition.— with an odd sagittal frenulum on each galea, and with an external bivalved lattice-mantle, produced by the anastomosing branches of the hollow radial tubes. Six to sixteen long styles are prominent over the surface of the mantle, and bear terminal coronets.

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

The genus Cœlographis is the simplest form of the Cœloplegmida, or of those Cœlographida in which the branches of the arborescent tubes are united on the surface of the calymma, and form a delicate bivalved lattice-mantle. In all these Cœloplegmida an odd nasal main style is developed on the apex of the galea, and this is connected by an odd sagittal frenulum with the mouth of the rhinocanna, Cœlographis differs from the other Cœlographida in the minimum number of coronal styles, viz., three on each valve, an odd anterior (nasal) and two paired posterior (tergal).

1. Cœlographis regina, n. sp. (Pl. 126, figs. 1a-1c).

Shell-mantle twice as long as broad, its frontal perimeter isosceles triangular, with a triangular excision at the base, its sagittal perimeter slenderly ovate. Nasal odd style twice as long as the