S43

Cenosphaera spp.

DESCRIPTION AND DIMENSIONS

"The specimens included in this group are several forms which all have spherical shells lacking any internal structure or spines. The pores are rounded to subrounded and regularly disposed with 8-14 on a diameter; most specimens are thick-walled. The shell itself is quite smooth and lacks marked ridges between the pores. Only those specimens greater than 90mu in diameter were counted." (from Robertson, 1975).

''The species composing this group all have spherical shells with no apparent internal structure or spines. The description of this group given by Robertson (1975) is followed except that all species in the study contained round pores regularly disposed, with 10-14 on a diameter. The shell in all cases was smooth with no ridges between the pores. Only specimens between 90mu and 150mu in diameter were counted." (from Morley, 1977).

Plate 4, figures 3a-d

S44

RECENT DISTRIBUTION

1. Robertson, 1975; "This group loads most heavily in factor 2 (subtropical). Its present distribution is almost cosmopolitan with lowest abundances in the Sea of Okhotsk and Bering Sea. At 18,000 YBP higher abundances are restricted to the south except for an unexplained extension to the north at about 160degE."

2. Morley, 1977; Fig. I-12; "This group loads highest in factor 3 (gyre margin). At present this generally cosmopolitan group is found most frequently in samples under subantarctic and southern subtropical waters. In addition to a general decrease in abundance at 18,000 YBP, the maximum area of concentration of this group is displaced northward by approximately 7deg."