S95

Spongaster tetras Ehrenberg irregularis Nigrini

Spongaster tetras Ehrenberg irregularis Nigrini, 1967, p. 43, pl. 5, fig. 2

DESCRIPTION "Shell roughly rectangular, usually irregular, spongy. Basically similar to Spongaster tetras tetras, with 4 or 5 central concentric lattice spheres, but differing from it by the shape of the patagium and angle between the "arms". "Arms" generally indistinct at 65 degrees - 79 degrees to each other, forming an oblique cross; rarely, this angle may be as low as 59 degrees or as high as 84 degrees." (from Nigrini, 1967).

DIMENSIONS "Length of longer side 136-263 microns; of shorter side 100-191 microns. Average radius of arms (measured from center of innermost sphere) 80-132 microns." (from Nigrini, 1967).

Plate 13, figure 2

S96

RECENT DISTRIBUTION

1. Nigrini, 1967, fig. 21; "Indian Ocean occurrences - S. tetras irregularis is absent from low latitudes. In middle latitudes it is sparsely distributed. Though rare in Recent sediments, it appears to be a useful member of the middle latitude assemblage."

2. Nigrini, 1970, fig. 20; belongs to a transitional assemblage derived by recurrent group analysis of North Pacific samples.