Figure 4 in REVIEW Exploring annelids in the age of Enlightenment and beyond: classification and bioluminescence

Figure 4. Plate XCIII of Rösel von Rosenhof (1755), showing two other types of 'little snakes' (i.e. microdriles) differentiated by him. The top half (subfigures 1–7) shows the 'little maggot-like snake' [now Chaetogaster diaphanus (Gruithuisen, 1828)], a predator species feeding on water fleas; these worms survived when cut transversely but did not regrow significantly. The bottom half (subfigures 8–16) shows the 'small sinuous water snakes with two fork tips' [now Aulophorus furcatus (Müller, 1774)], which were commonly seen sitting on the duckweed and swimming away immediately if disturbed. When cut into two parts, this worm, to Rösel's amazement, regenerated into three parts: the rear part always fell into two parts (by fission of a paratomic specimen).