Fig. 3 in The architecture of the physid musculature of Physa acuta Draparnaud, 1805 (Gastropoda: Physidae)

Fig. 3. (A) Transverse view of the body at the level of the lung floor as seen from below showing the physid muscle s.s. (Pm) and columellar muscle (Cm). Fibres from the Pm (Plu) and columellar muscle (Cm) cross the lung floor (fine detail indicated in upper right hand corner of the lung floor). The lung floor is surrounded by mantle collar tissue. (B) Dorsal view of P. acuta with the visceral hump removed to show the dorsal components of the columellar muscle (Cm). These have been flattened slightly. No detail is shown on the lung floor. (C) Above – dissection of the columellar muscle (Cm) and its four elements (slightly flattened). Below – detail of Cm overlying Pm4 and Pm5 fibres as they pass into the foot.