S121

Hexapyle spp.

Hexapyle dodecantha Haeckel, 1887, p. 569, pl. 48, fig. 16; Benson, 1966, p. 275, pl. 18, figs. 14-16, text-fig. 20

DESCRIPTION "Test consisting of a double pylodiscid shell; with outer shell larger than that of [Discopyle? sp] but with similar arrangement of twelve radial spines and, in several specimens, with one, two, or three radial beams each extending across the tubular spaces through the shell; with or without a large but irregularly-pored lattice covering the surfaces of the outer shell. Latticed covering, when present, with numerous (50 or more) radial spines arising from its surface and branching at a common level; in a few specimens, the branches of these spines anastomose to form part of an outer triangular or ellipsoidal latticed shell which was never observed fully developed; completely developed tests, therefore, not discoidal. Innermost structure within first pylodiscid shell not observed but may consist of a central node from which radiate the three radial beams mentioned above." (from Benson, 1966).

DIMENSIONS "length of base of inner triangular pylodiscid shell 18-43 microns, of outer pylodiscid shell 80-137 microns, of altitude of inner shell 20-42 microns, of outer shell 74-128 microns; length of base of outer triangular shell covering double pylodiscid shell 113-185 microns, of altitude 122-154 microns." (from Benson, 1966).

Plate 16, figures 1a-c

S122

RECENT DISTRIBUTION 1. Benson, 1966; (Hexapyle dodecantha); identification of this species frequently depends on orientation.

"Numerous, relatively large ellipsoidal shells were counted as a group designated as Litheliacea unidentified if some indication of inner latticed girdles were observed....This group is common to rare at all stations in the Gulf except 203 and 214 where it is absent. It occurs in greater numbers in the southern Gulf; thus it is parallel to the distribution of the members comprising it."

2. Molina-Cruz, 1975, Code S53; used in factor analysis of southeast Pacific assemblages; cf. Appendix 10 for percent S53 at each station.