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Actinomma acusosum Blueford, 1982

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Description: Three concentric shells, 84, 24, and 12 Ám in diameter. Outer surface with many (more than 15) thin-bladed spines 12 Ám in average length and many by-spines. Outer pores circular, nearly equal in size (6-10Ám), closely packed, 7-12 Ám between pore centers. Inner pores circular, hexagonally framed. Numerous thin radial beams connecting middle and inner to outer shell. Innermost shell obscure.
Holotype: Plate 3, figure 4, DSDP Site 77, core B-22, section 5, 60-62cm, England finder V 13/1 (USNM 315054).
Distinguishing features: Small size and three shells, of which outermost has thin-bladed spines and circular pores. Actinomma leptodernum (J°rgensen, 1900) has unequal, roundish oval pores and larger shell diameter
Comments: Bj°rklund (1976b) revised the genus Actinomma and gave an account of some Atlantic forms.
Derivation of name: In reference to the many thin spines, from the Latin acus, needles and osus, full of.
Occurence:Actinomma acusosum is relatively rare at both sites. No upper limit is known; a possible lower limit between cores 45 and 46 at Site 289 that is not correlative with Site 77 is indicated.
Blueford 1982


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