Fig. 4 in The ultrastructure and building of graptolite dissepiments

Fig. 4. Dendroid graptolite "Dictyonema" sp. 1. Fine structure of the dissepiment, Caradoc limestone, borehole Chudovo, depth 33 m, Estonia, SEM micrographs, ZPAL G.39/2. A. Broken expanded base of the dissepiment revealing fusellar core and cortical envelope. B. Broken dissepiment in the middle part showing central core. C. Layering of the cortical envelope. D. Ultrastructural details of fusellar and cortical fabrics in the dissepiment.