A very fine, almost complete internal mould showing features of particular interest: on each of the thoracic tergites on both sides is a prominent fulcral articulation (a kind of elbow or semi ball and socket joint). The fulcral articulation presumably acted for articulation during normal movement and may also have helped to prevent overgliding of the thoracic pleurae during the completion of enrollment. The hyperstome impression is also clearly visible. From Trawsfynydd, Gwynedd, Wales.
Size: 60mm by 35mm on block 67mm by 50mm
Size: 60mm by 35mm on block 67mm by 50mm