| Home> Cenozoic> Miocene>
 

List species

Actinomma holtedahli Bj°rklund, 1976

Description - Add description

Based on examination of 25 specimens, the test is composed of one (?) spongy medullary shell, 50-75Ám in diameter. Two cortical shells, outer and inner basically of same structure, outer shell, in most cases, a little thinner with smaller pores, 10Ám in diameter than the inner cortical shell with pores about 20Ám in diameter. Diameter of outer cortical shell, 200-250Ám, while the inner is roughly 20-40Ám smaller. The medullar shell is connected to the two cortical shells by numerous (more than 15) thin cylindrical, radial spines, while the two cortical shells are connected with additional bars.
Dimensions of holotype: Outer cortical shell, 250Ám, inner cortical shell, 210Ám, and the medullary shell about 75Ám. Holotype from pl. 20, fig. 9. Holotype from Sample 338-15-4,130-132cm.
Remarks: The genetic placing of this species is rather questionable, as it was not possible for the observer to state wether the medullar shell consisted of one or two shells, as illustrated in Dumitrica (1972, pl. 7, fig. 4-6), and, consequently, should have been referred to the genus Rhizosphaera.
Bj°rklund 1976


Description

 

Images

 

Synonyms

 

References

 

Distribution

 

Discussion / Comments

 

Web links