Fig. 2

NHMM BM MK.151, Hemipneustes striatoradiatus (Leske, 1778) encrusted by the left (= attached) valve of Pycnodonte (Phygraea) vesiculare (Lamarck, 1806), from the Nekum Member (Maastricht Formation) of quarry ‘t Rooth, Bemelen (southern Limburg, the Netherlands). a Apical view, anterior towards top of page. Pycnodonte (Ph.) vesiculare attached to posterior of apical system and much of the posterior test. The long, straight dorsal margin is arrayed sub-perpendicular to the long axis of the echinoid. For numbering of Hemipneustes ambulacra and interambulacra, see Donovan et al. (2014, fig. 2a). A small black asterisk marks to positions of the (pale coloured) small oysters in the anterior ambulacrum. ‘In’ and ‘out’ mark the approximate incurrent and outcurrent positions of the oyster. (b) Posterior view showing how Pycnodonte (Ph.) vesiculare extended to just above the periproct. (c, d) Left and right lateral views, respectively, showing Pycnodonte (Ph.) vesiculare extending across the posterior test. Stated orientations refer to the echinoid test. All scale bars represent 10 mm