N29

Peripyramis circumtexta Haeckel

Peripyramis circumtexta Haeckel, 1887, p. 1162, pl. 54, fig. 5; Riedel 1958, p. 231, pl. 2, figs. 8,9; Petrushevskaya, 1967, p. 111, fig. 64, I-II, fig. 65, I-II

DESCRIPTION "Cephalis small, ovate, hyaline, bearing a short, excentric, vertical apical spine. Collar stricture slight, with four collar pores in the one specimen which could be examined from the apex. In some specimens, one to three (?) short, downwardly-directed spines penetrate the thoracic wall near the collar stricture. Thorax rather acutely conical, in some specimens subcylindrical below, consisting principally of 8-11 longitudinal rods joined by transverse bars which are usually not continuous around a circumference. Thoracic pores thus formed are rounded-quadrangular, increasing in size distally. From the longitudinal and transverse skeletal bars of the thorax arise numerous short, forked spines; the terminations of these spines are in some specimens joined by delicate siliceous threads which thus form a loose, irregular, incomplete network surrounding the main surface of the thorax." (from Riedel, 1958).

DIMENSIONS "Total length usually 100-270 mu (to 320 mu according to Haeckel) maximum breadth 85-150 mu." (from Riedel, 1958).

REMARKS

1. Benson's (1966) description and dimensions of this species (p. 426) are consistent with the above.

Plate 21, figures 4a, b

N30

RECENT DISTRIBUTION

1. Benson, 1966; "very rare in the Gulf [of California]."

2. Molina-Cruz, 1975, Code N23; counted together with Plectopyramis dodecomma Haeckel, but not used in factor analysis of southeast Pacific assemblages; cf. Appendix 10 for percent N23 at each station.