Fig. 8. Mastigograptus aff. tenuiramosus. A in The ultrastructure, development, and systematic position of the graptolite genus Mastigograptus

Fig. 8. Mastigograptus aff. tenuiramosus. A. Thecal base of Fig. 6B. Scale bar 50 µm. B, C. Fractured thecal bases, and occluded autotheca (arrowed) (ZPAL G.30/17). Scale bars: B, 100 µm, C, 50 µm. D. Thecal base on main stem, with occluded autotheca (arrowed), a needle preparation from ZPAL G.30/18. Scale bar 20 µm. E. Stem, looking obliquely proximally, with two thecal bases (ZPALG.30/15). Scale bar 200 µm. F, G, H. Successively more distal cross−sections of thecal bases. Scale bars 10 µm, 50 µm, 100 µm. I. Thecal base with occluded autotheca (ZPALG.30/17). Scale bar 50 µm. J. Diaphragm of stolonal triad in thecal base, looking proximally (ZPALG.30/15). Scale bar 10 µm. K. Stolotheca looking proximally with adjacent thecal base displaying astolothecaltriad,seeH(ZPALG.30/11).Scalebar200µm. L.Crassal,fusellarandcorticaltissuesinthecalbase(ZPALG.30/17).Scalebar5µm. M."E.T. head" of thecal base, with central occluded autotheca (ZPAL G.30/4). Scale bar 50 µm.