Fig. 4. Mastigograptus aff. tenuiramosus. A in The ultrastructure, development, and systematic position of the graptolite genus Mastigograptus

Fig. 4. Mastigograptus aff. tenuiramosus. A. Fractured wall of stolotheca. The head of a fusellus is arrowed (ZPALG.30/9). Scale bar 10 µm B, C. External ornament on stolothecae (ZPAL G.30/10). Scale bars 100 µm, 50 µm. D. Sectional view of stolonal triad on main stem, looking distally (ZPAL G.30/11). Scale bar 50 µm. E. Stolonal triad on main stem, looking proximally; diaphragm at base of occluded autotheca (arrowed) (ZPALG.30/12). Scale bar 50 µm. F. Base of diaphragm on main stem, looking distally, and showing two pores (ZPALG.30/13). Scale bar 10 µm. G. Portion of stem with monopodial branch to right. a, occluded first thecal base on branch, with short stolotheca. b, borings on main stem (ZPAL G.30/14). Scale bar 500 µm.