Figure 11 in Systematic assessment of the Atelostomata (Spatangoida and Holasteroida; irregular echinoids) based on spine microstructure

Figure 11. View of the cylinder of spines of atelostomate echinoids of early–middle Albian age (Falkland Plateau; A, GZG.INV.94999; B, GZG.INV.95000). A, view on the inner side: pores are arranged in a horizontal pattern (right half of the image), but from approximately half of the image the pattern changes to helicoidal. B, view on the outer side: pores are arranged in a helicoidal pattern throughout. Scale bars: 20 μm.