Fig. 2 in Silurian retiolitid graptolites: Morphology and evolution

Fig. 2. Ancorae sleeve membranes in Silurian retiolitids. A, B. Spinograptus praerobustus Lenz and Kozłowska−Dawidziuk, 2002, specimens with preserved thecal and ancora sleeve membranes, Cornwallis Island, Arctic Canada, ABa3−98, 21 m, Colonograptus praedeubeli–C. deubeli Biozone, Wenlock. A. ZPAL G.37/1; A, stereopair of exterior proximal end showing ancora, well−preserved sicula, base of theca 11 (directly below sicula), double fusellar walls, thecal ap1 ertures and spino−reticular genicular processes; A2, reverse view showing ancora and ancora umbrella, and partially preserved thin fusellar layer that fills in space between the zigzag (bandaged) lists; A, Proximal−lateral stereopair view. B. Stereopair showing sicula, theca 12 on lower right side of sicula, aperture of 3 theca 12, inner and outer (ancora sleeve) fusellar layers, and thin nema, GSC 107928. C. Proximal end of Retiolites angustidens Elles and Wood, 1908 with broken ancora umbrella, NMW 91.52G.812, 500 m south of Stenkyrkehuks fyr, Gotland, Sweden, Lower Visby Marl, uppermost Llandovery; C1, ventro−lateral view; C2, view to the inside of rhabdosome showing sicula and thecal walls. Abbreviations: as, ancora sleeve; s, sicula; th, theca.