FIGURE 27. Rhadinacanthus longispinus dorsal spine histology. 1, 2 in The diplacanthid fishes (Acanthodii, Diplacanthiformes, Diplacanthidae) from the Middle Devonian of Scotland

FIGURE 27. Rhadinacanthus longispinus dorsal spine histology. 1, 2, transverse section of anterior dorsal fin spine NMS G.2015.11.1 from Broad Taing, Orkney: 1, whole section indicated by white line; 2, magnified area; 3–5, transverse sections of posterior dorsal fin spine NMS G.2014.4.33 from the slates west of East Murkle Bay, Caithness (Mey subgroup): 3, section through insertion area; 4, 5, section through exserted part of spine; 6, transverse section of posterior dorsal spine NMS G.2014.33.2 from North Ronaldsay (Rousay Beds). Scale bars equal 1 mm in 1, 3, 4, 6; 0.1 mm in 2, 5.